At the time of writing, I have a bounty on question Make the hot questions more relevant to the Stack Exchange site you're on (aka I shouldn't have to see a bible study on Stack Overflow).
The bounty ends at 0655h on Sep 13. It is currently 1338h on Sep 12 (times already converted to UTC). The bounty banner on the question page correctly states that it is "an open bounty worth +150 reputation from Popular Demand ending in 16 hours."
However, the bounty tab in my profile lists the bounty as being in "grace period." Hovering over the "grace period" indicator doesn't bring up a tooltip.
After reading Where's my bounty gone?, I noticed that the tooltip for the bounty on this page states that the bounty is still open, although it ended over a day ago. Not sure if this is the same bug.