Check your date with the "date" command.
root@mythtv:/root# date
Wed Apr 1 23:12:09 EDT 2009
Verify that date against time.gov.

If it seems off, you can sync up with a time server manually with the 'rdate' command:
root@mythtv:/root# rdate -s nist.expertsmi.com
That's just one of the time servers I found - I don't remember where. After that, do another check and you should see your time sync up with time.gov, and your recordings will start on time. When I get around to looking into what happened with my time server synchronization, I'll write a follow-up post.