In my haste, I accidentally awarded it to David Carlisle's answer instead. (I did read the warning about making sure it was the correct answer to award it to: it was the fifth such time that I read that warning, in fact, because I tried to award the bounty a few times, not having carefully kept track of precisely when it would be possible to award it.) While David is certainly a wonderfully helpful person on the site, I would really have preferred to award it to a user with lower reputation.
When I tried to offer another bounty to award it to them, however, I found the minumum bounty has risen to 200. (It appears as though each question can only be awarded one bounty of any given value!)
Is there any way for the mods to undo my bounty to David, and allow me to reward a +100 bounty to user47919 instead? Alternatively: can they shift the recipient of the bounty themselves?