This is a trivia question, the only reason I dare to bring this up is because we have entertained similar curiosities here on Meta about the functioning of MO.

An old accepted answer of mine from 2011 received it's tenth upvote a few days ago. This should trigger a bronze and a silver badge, but none appeared. Just out of curiosity, I wonder: is this because old posts have a separate badge queue that only runs occasionally, is it because posts from before MO migrated to SE no longer participate in the badge circus, or is it just a random glitch?