During the second bounty period, if you answer did not result in an automatic bounty:
Approximately 24 hours after the end of the bounty period (once the grace period ends), if the bounty starter has not manually awarded the bounty, the bounty may be awarded automatically.
If the author offered the bounty, and accepted an answer that was posted during the bounty period, that answer is awarded the bounty. Answers created or accepted before the bounty period are not eligible to be awarded the bounty automatically in this manner.
Otherwise, all or half of the bounty is awarded to the highest-scored answer out of those which...
- ...were posted after the bounty was started
- ...have a score of at least +2
- ...were not written by the bounty starter
If the chosen answer is accepted (at any time), it will receive the full bounty; otherwise, it will receive half the bounty. If two eligible answers have the same score, the older answer is chosen.
If none of these conditions apply, the bounty is not awarded to any answer, and is not refunded to the bounty starter.
So I think:
- You answered before the bounty period.
So, even though bounty-offerer accepted your answer, they will have to manually award the bounty to you.