The rules for valid wills vary significantly from state to state. If they are worried, a quick call to the attorney who drafted them may be the most cost effective and reassuring way to verify you are recognized.
That said if there many changes from when the will was originally drafted, it may be time to have an attorney redraft the will. I come back a bit to having an attorney look at this as Estate Planning can get strange and complex for what would otherwise appear to be simple and straightforward issues.