Hi Lisa,
First off, are you using a modified report for your check? That would be the first thing I would check. If you are, you might want to look more closely at those modifications to see if those might be causing it. Personally, I have never heard of this kind of thing happening.
The date field on the check face is a different field than the date field on the stub, take a look at it in Report Writer and see if you notice any anomalies.
Kind regards,
Leslie