I recently bountied a question of mine and got the answer to the question, so I answered my own question. Basically, I asked the question on two sites and bountied both of them. One person on another site answered my question, so I gave them the bounty. I then answered the question on the other site to tell the users I knew the answer and whatnot. I never go the bounty back (even though I never expected to).
What are the reasons behind this? I can't find anything in the bounty info page that SE has.