This is closely related to this question.
It seems my "nice answer" badges are out of sync too, as in the related question.
I just got a notification informing me that I received the badge for an answer that reached 10 votes many moons ago, while the one that recently achieved 10 upvotes is this one.
Except for some maniac tendency to tidiness, the whole matter doesn't disturb me that much :), but I think it may be related to a "nice answer" badge I received some time ago, and the question was subsequently deleted. I don't have a pointer to that question, but perhaps the developers can trace it from my "nice answer" badge board.
Although this issue is already known, I am reporting this as a bug just to inform about the possible correlation among the deleted question and the out-of-sync.