It was an inadvertent comment from Sinfield, the illustrious captain who is normally so thoughtful but careful with his words on such occasions, that set the pair off either side of Brian McDermott, who managed to hold himself together a little better.
But the players – dictating on-field matters together for well over a decade and, more importantly, best of mates – had just won the treble for the first time in what was also talisman Sinfield’s final game for the club along with fellow greats Jamie Peacock and Kylie Leuluai.
If you can’t relax after that, when can you?
Undoubtedly Sinfield departs, making the short journey across the corridor at Rhinos’ Kirkstall training facility to Yorkshire Carnegie, as one of the finest players of his generation.
The numbers alone are staggering: 521 games for Leeds, 86 tries, 1,792 goals – the last of which delivered Rhinos their seventh Grand Final under his leadership on Saturday night – and let us not forget the 40 drop goals pinged over since he debuted back in 1997.
The total of 3,968 points leave the former England captain as the third highest points scorer in the sport’s long history.
Was victory over Wigan Warriors in a fittingly epic Grand Final – the best yet – the perfect finish?
Sinfield did not hesitate, admitting: “Without a doubt. To top it off – the treble in my final year – it’s unbelievable really.
“I’m really, really thankful, really proud. The lads I get to play alongside every week and train with every day have been huge this year particularly, Mac (Brian McDermott) as coach, the backroom staff, everyone involved with the club has created a place where it’s been very, very special to play in and bow out.
“They all stay with you (Grand Finals). The good thing about winning the final game is that all through pre-season, especially for these guys now, it will be there with them and in pre-season when it’s tough it really spurs you on to go even further.
“For me it’s slightly different but I will certainly remember it.
“I remember them all but to finish on an ending like this – against a great team as well, I must add – and for it to be so tough out there to come through was brilliant.”
Battle weary and wounded after all that toil, it was almost obligatory that Sinfield should pick up another scar for his efforts.
Rather than Wigan’s swarming defence, though, it was his own team-mate, Man of Steel candidate Adam Cuthbertson, who left him stitched up – and in stitches.
“He just said to me I will always remember him every time I look in the mirror,” smiled Sinfield, about the Australian prop who was left bandaged up, too, after an almighty clash of heads.
“I have to say I’ll always remember him anyway; he’s been brilliant this season and the impact he’s had in year one, he’s the best overseas signing.
“Kylie’s been here a long time and is the best overall but after the season he (Cuthbertson) has had, he’s been brilliant.
“He’s got a fair gash as well so every time he looks in the mirror he’ll see me, too!”
Sinfield’s career has been more gilded than he could ever have imagined when joining Leeds from Oldham junior side Waterhead.
“When you play amateur rugby you’re just desperate for a chance, for an opportunity,” admitted the player, who won the Golden Boot as the world’s best player in 2012.
“It’s not really sunk in if I’m honest. I think when I get on a sun lounger, with my feet up, I’ll reflect a little and it will start to sink in what this team has achieved this year, how good it’s been.
“There’s memories I’ll never forget. Some of those players – Maggsy (McGuire), Rob (Burrow), Jamie Jones (Buchanan) I’ve grown up with and been alongside them for 15 years.
“Those friendships will never go; we’ll meet up at 50 or 60 at reunions and those friendships will be exactly the same.
“Wow. I feel very proud but really humbled as well – very, very fortunate. What a great team that is.
“And it doesn’t end (at Old Trafford) for those boys. It carries on and, as Maggsy has said, I’m not that far away.
“I’ll become a supporter now and help the team any way I can moving forward, especially some of our young boys who are absolutely brilliant and ready to be thrown in and given an opportunity.”
There is a realisation that, as well as he may prosper in the 15-man code, he will never experience highs such as this weekend.
“I don’t think I’ll ever be able to create friendship and memories as I have done here as they’ve been built since I was 13,” Sinfield added.
“And I’m certainly not going to play for another 22 years. How do you recreate that? I don’t know. It’s something really special. But I’ll look forward to the future.”