I have read various posts on bounties, as well as the help center. There, I find the following:
If you do not award the bounty within 24 hours of the bounty period ending, half the bounty value will be automatically awarded to the top voted answer posted after the bounty start, provided it has a score of at least 2. If no new answer matches this requirement, no reputation will be awarded at all, and the reputation used on the bounty will be lost forever.
Now I recently ran into a situation where an old question (to which I had posted an answer several months ago) was bumped with a (small) bounty from the OP. I decided to give it another shot, and improved my original answer with a substantial edit (which eventually led to my answer being accepted by the user, and several additional upvotes).
However - the user did not manually award the bounty; and given that my answer was not "new" (in the sense that I did not post an answer after the start of the bounty period), the fact that it was "new and improved" apparently does not make it eligible for the "automatic 50% bounty".
Now I don't care too much about 25 points - but I wonder: does this make sense? Would the "auto" rule make more sense if it was modified to award the bounty automatically to one of:
- new answer with > 2 score
- edited answer with > 2 score increase
- accepted answer with > 2 score
in all cases, it would be awarded the highest-scoring answer that meets at least one of these criteria.
*) In the context of "the exception that proves the rule", the verb "prove" actually means "probe, test"; in other words, it is by examining the exceptional cases that one gets a better understanding of the (limits of the) rule.