looks like he got into his head with that?
It's unclear what he said, but he basically called Murray out for challenging the line call. Murray didn't have any challenge, but he expressed his disagreement with the call anyway. Federer didn't like it.
I really think the effect is being overstated a bit. Federer played some great aggressive tennis to put pressure on Murray in that service game. And that wasn't the first big point that he botched with a cross-court forehand.