The FAQ on bounties:
The bounty period lasts 7 days. Bounties must have a minimum duration of at least 1 day. After the bounty ends, there is a grace period of 24 hours to manually award the bounty.
If you do not award your bounty within 7 days (plus the grace period), the highest voted answer created after the bounty started with at least 2 upvotes will be awarded half the bounty amount. If there's no answer meeting that criteria, the bounty is not awarded to anyone.
Taken together with related MSO discussions, I understand the purpose of the grace period is to enable an offeror to manually award a bounty before that decision is automated on their behalf.
However, answers can (rightly) still be posted during this grace period; are they eligible to receive the award (manual or automatic)? Will a question that only receives its second upvote or is accepted during the grace period still receive an automatic award?
What should the correct behaviour be here, irrespective of the current implementation?