Now he is the Ireland captain, Sexton has a different relationship with officials, and felt he had not pushed his point across enough in Ireland’s opening win over Scotland.
This Saturday in a 24-14 success against Wales, Sexton was not going to let a decision slide if he disagreed with it, as was the case on more than one occasion with referee Romain Poite.
In Sexton’s favour, there are few players who understand the game better than him, and rugby’s lawbook is so open to interpretation that some of his arguments were quite convincing.
However that overlooks the first thing every rugby player learns: ‘The referee is always right’.
Whether Sexton was correct about Taulupe Faletau stopping the ball from emerging from a maul on 16 minutes being illegal or not, the fact it was virtually his first interaction with Poite in the match and felt more like a lecture from the Ireland skipper than a question, is an issue.
That particular scenario of whether a defending team should be rewarded with a maul for preventing its release is worth a column on its own, and in this case it was probably the right call from Poite, albeit to a flawed law.
What is certain though, is that Sexton’s approach will probably not have endeared him to the man in the middle.
Rather than being right, captaincy is more about getting on the right side of the referee, one of the few skills Sexton still has to work on and something he felt held him back against Scotland during his interaction with Mathieu Raynal.
To be fair to the Leinster fly-half, he was much better later in the Wales game when CJ Stander had been penalised at a breakdown five metres from his line, using a more conciliatory tone while sowing some doubt into Poite’s mind over Welsh clearouts.
That ability to influence a referee is increasingly important in the modern game, and some of the great captains of recent times – Richie McCaw and Sam Warburton spring to mind – trod the line as well as anyone.
There is a very strong case to be made that it should not be that important. A lot has been made of the difficulty for teams and captains whose first language is not English to build the same rapport with officials as their English-speaking counterparts.
And do we really want the ability of a captain to get a referee onside to factor into the final result?
Yet, rugby is so complex that a captain who can read what a referee wants and convey that to his team, is a major asset.
Sexton may know the lawbook better than either McCaw or Warburton did in their playing days, but that in itself is not enough.
He has a well-documented chequered past with officials, most notably with his infamous: “I know you hate me, but I’m the captain now – you have to talk to me,” line to Pascal Gauzère during a 2018 clash with Australia.
If anything, being captain provides Sexton with a legitimate platform to voice his gripes on decisions, but as he admitted last week, the important part is judging how and when to do so.
In that sense, Warburton was a master. The most obvious case was on the 2017 Lions Tour, when in what turned out to be his final act as a player, Warburton convinced the very same Poite to reconsider his decision to give the All Blacks a last-second penalty that would likely have earned them a series win over the Lions.
Again, it is not about whether it was the right call from the officials or not, but more Warburton’s remarkable ability to guide them gently to find in his favour.
Go back a little further and it was a player not a captain who was able to swing a rather important game by getting a referee onside. Jason Leonard’s introduction and immediate rapport with referee Andre Watson in the 2003 World Cup final allowed England to stem a flow of scrum penalties and edge out Australia to lift the Webb Ellis Cup.
On the other side of the ledger, it is not just Sexton who has had his difficult moments. Who could forget James Haskell being told by Poite that it was not the referee’s responsibility to explain how England could counter Italy’s no-ruck tactics in 2017?
And even this season we have seen Luke Pearce get so fed up with Saracens skipper Jackson Wray that he told him to go away and elected another player, as it happens, teenager Manu Vunipola, with whom to talk.
As the number of angles and slow-motion replays increase in the game, it feels as though the referee’s authority has never been questioned more.
It probably is not helped when officials are openly called out by World Rugby as they were during the Rugby World Cup.
With that being the case, the ability to get on the right side of a referee is one of, if not the most important skills for a captain.
Even over the course of 80 minutes, Sexton showed that he is improving in that area. The challenge now is to reach the standards set by his former Lions captain Warburton.