I have this answer of mine. It is accepted and has 10 upvotes (and one downvote) and is the first answer of the question. The last upvote is more than 3 days old. However no Enlightened badge was awarded to me. According to the definition of the badge:
Enlightened × 58749 First to answer and accepted with at least 10 upvotes
However, the rule might be a bit different: not 10 upvotes, but rather score of 10, otherwise why the 3 day delay in distributing the badge?
I am marking the post as bug, because I think either the rule or the definition should be changed.