Thanks everyone for your responses. Helped me calm down. The more I thought about it, the more I realized that since you have 7 days to do the 90 day after the date and I will be at airport immigration within that time frame, there should be no problem. And, as others noted, I have never had them check my 90 day at the airport.
But, there could always be a first! That is one of the exciting things about Thailand