Thanks for your input. The User Cleanup is set to 30 days and his last sync was on or about June 1st. The Miscellaneous Events log does not indicate any warnings or the user being removed. And I did not delete him, either. Unfortunately, he is traveling and will not be back in the office until Friday. Is it possible that he deleted himself from the device? I'm not even sure how to do that without a device wipe.
Feedback response number WEBB8UZPSK created by Anita Myers on 06/06/2012