I don't think it'll be a problem but be aware of potential rate changes. I got a fantastic deal minivan using the coupon and my AAA code ($278 total for 12 days). When I returned the car, they gave me a receipt for $695. I went to the counter and the agent, who was very nice, explained first that he'd fix it and then told me that my pick-up time was 12:01pm (vs 11:45am on my reservation) and it kicked it into a different category. Apparently noon and midnight are cut-offs for National. They never even asked for the coupon or my AAA card so that went fine. You may want to ask if the rate will change, other than possibly for the couple of hours, when you pick up.