Honestly no idea if it came out after from the team, I know Kravitz got it from someone in the garage (by 'know' I mean it's what he said so...hmm) during the race, which prompted the commentary chats.
More than possible he was just slow but I find it baffling to think that someone fighting for...
Little bit about it here;
http://formulaspy.com/formula-1/formula-1-news/rosberg-troubles-related-brake-problems-26590
I'm surprised how little it was mentioned considering Brundle, Kravitz and the other (easily confused) one spoke about it a few times during the race.
Probably had more to do with Rosberg having issues with his car though?
Pretty sure during the race they were told by Mercedes that he had brake issues.