<p><em>I've determined the answer to my revised question. I'll post it here since I was unable to find a satisfactory answer on Meta SO or any of the other meta sites that popped up when I did a google search of this problem. It's still not clear what would happen if the bounty holder had unaccepted my answer during the grace period.</em> </p>

<p>The answer to "updated" question above is: </p>

<p>Yes, there can be a substantial delay after the grace period before the bounty is auto-awarded. In this case there was around a 16 hour delay. You can tell whether the bounty was auto-awarded (or won't be) once the bounty label is removed from the bottom of the question (where it goes along the bottom border). Before this border is removed, the bounty is not "resolved" yet. </p>
