I typed up a question in the FeedBurner forums to ask if anyone knew what the problem might be, and then, as I often do, thought I should investigate the issue a little more on my own first. I found the Feedburner FeedMedic under the Troubleshootize section that shows you any errors that have occurred with your feed. There was one that kept repeating:
FeedBurner had trouble retrieving your Source Feed: https://dan.hersam.com/feed/atom/
The error message is: Your server disconnected us before sending the full source feed content. If your blogging platform is TextPattern, this is a known bug, and a fix can be found here: http://forum.textpattern.com/viewtopic.php?id=11247
The fix is in functions.php which you can download from Mark’s site.
If you’re getting this post via e-mail from your FeedBurner subscription, then it worked.