On the last cron run, I have quite a few of these in the log:

Type: php
Date: Thursday, November 13, 2008 - 15:15
User: Anonymous
Location: http://tips-q.com/cron...
Referrer:
Message serialize() [function.serialize]: Node no longer exists in /var/www/queer/sites/all/modules/feedapi/feedapi.module on line 1125.
Severity: error