Delta has made a policy change regarding award tickets. Effective last month, and with five days notice, members must now cancel or change award tickets at least 72 hours before your scheduled departure time or you will forfeit your miles. The taxes and fees for award travel cancelled within 72 hours will be refundable only upon request. For changes and cancellations made at least 72 hours prior to departure, Diamond and Platinum Medallion members will continue to get fee waivers, while others will pay reissue and redeposit fees.
Bottom line: Many SkyMiles members have been waiting until the last minute to change their award tickets because the cost in miles would often go down at the last minute. Delta found that over the past year, more than 1,000,000 award tickets were cancelled or changed within 72 hours of departure.