I posted this answer to my own question on which I had set a bounty. I lost the rep immediately when I set the bounty = OK, that's expected. I didn't get the bounty back when I added the best answer and accepted that = not OK, I had expected the bounty, based on how Superuser.com works.... so why didn't I get my bounty back?

(Please note that I'm not whining, I just want to understand the reason.)