Open surgical repair of abdominal aortic aneurysm (AAA) is often regarded as a near-permanent operation with little long-term complications. Reported herein is a case of delayed rupture of an enlarging AAA sac after open repair requiring re-exploration in a patient presenting with flank pain and ipsilateral hydronephrosis. The natural history of a large, excluded aneurysm sac after open AAA repair, hypothesized etiology for this rare occurrence, and proposed diagnostic and therapeutic algorithm are described.