LastLogon is 24 days old and still more recent thean LastLogonTimeStamp

I know how this is suppose to work, but does not seem to be working properly.  I have a disabled user who has a LastLogon of 3/4/2013, and the LastLogonTimeStamp is still older at 2/23/2013.  What should I check? Is my msDS-LogonTimeSyncInterval possibly off?  Can non-interactive logons(webmail using adfs) cause this problem?

Thanks,

Dan

Dan Heim