FeedBurner Emails Worked for Over a Year, But Stopped Sending This Month

[Jamie Gough]

The site is http://dirtanddenim.com.  The feedburner emails were delivered to subscribers for more than a year, and then randomly stopped going out earlier this month (a post from May 6 went out fine, but a post from May 9 did not).  I've tried changing the publication date, republishing later, cleaning up the code from the visual editor, but nothing has helped.  Also tried deactivating and then reactivating the publicity emails in feedburner, but again, that did not help.  Do you have any ideas about what might be going on here?

Thanks in advance for your help.