Cronjobs get the wrong time stamp in mail record

[David Liontooth <liontooth@cogweb.net>]

I'm running a script as a cron job on four machines, and get an e-mail every
time the job is completed. On three machines, the time stamp is the time of
the completion of the job; on the last one, the time stamp is five minutes
earlier. I've checked the time on the machine; it's correct (maintained
with ntpdate). What could possibly be causing a mail to be timestamped five
minutes (consistently) before the cron job it reports is over?

Dave