Called today to book a 3 night stay for November using 2 free certs (expirations of July 19th and sometime early next year) and 1 night of points. I didn't mention expiration, but rep proactively extended it when she noticed it wasn't going through because of the expiration. She was kind of mumbling to herself when doing it and sounded like she had to select a reason because she said a date about a week after my trip and then said "courtesy adjustment". Obviously YMMV, but I think being close to expiration and requesting a booking helped