The bounty documentation includes the following explanation about auto-awards:
If the bounty was started by the question owner, and the question owner accepts an answer during the bounty period, and the bounty expires without an explicit award – we assume the bounty owner liked the answer they accepted and award it the full bounty amount at the time of bounty expiration.
On this question, Gershon Gold (who asked the question) started a bounty on Oct 29 and did not award it explicitly to anybody. I offered my answer a few hours before the bounty started, so if it were somebody else's bounty I would not have been eligible. However, Gershon accepted my answer on Oct 30, so the documentation seems to say that I should have gotten the award. However, the bounty actually expired without being awarded.
Gershon answered during the bounty period and then deleted his answer. I don't know if that's relevant. I have no idea if he accepted another answer before accepting mine.
Should I have gotten this bounty? If not, why not?
As a moderator I obviously don't need the reputation to unlock privileges. I'm just trying to understand what happened because unexpected behavior is a puzzle and I'm curious. Plus, the warm fuzzy feeling of actually seeing that rare-for-me bounty notice next to my answer is nice. :-)