A question's revision history has shown bounty events for quite some time now. Since then, Stack Exchange has also added support for bounty remarks.
I would like to request that bounty remarks be added to the revision history, as well.
For example, consider the revision history for this feature request.
This may be more prevalent on Meta SO than other sites, but when there are multiple bounties on a single question I think that it would be helpful to have a history of the bounty remarks to clarify precisely why the bounty was offered, rather than a series of "Authoritative reference needed" notices.