Surprised no one has mentioned the Kevin Na vs Dustin Johnson no-concession/concession.
DJ struggled this week, just didn't seem like he was much into it. But it definitely appeared to me that when Na reminded him that it is just standard protocol in that format to affirm an opponent's conceded putt - it didn't help DJ's mindset going forward.
I don't typically make much of an issue out of such formalities... yet I think Brandel had a good point that perhaps DJ had done this prior in their match (scraped away a gimme without it being formally conceded) and that prompted Na to say something. I also agreed with one of the other analysts who said something to the effect of, "It's not that what Na did was improper, but that perhaps it was a conversation that would've been better had behind the scenes and not on-camera."
Na told his version, stating that he was basically reminding DJ that while he wasn't going to take away the halve for the hole and considered it good, it is technically not good until an opponent tells him.
Na went on to win, although it was essentially nothing more than a consolation win for him as he couldn't advance. At the end of the match... let's just put it this way - DJ didn't appear too interested to invite Na over for tea and crumpets afterward. DJ also refused to talk to the media for the post round.