I recently passed security in DTW. It was a one day R/T BWI-DTW-BWI. I accidentally used my BWI-DTW used boarding pass on the return, and passed security. When I looked at the pass afterwards for the flight number, I realized the officer had made a mistake. I reported the error and circumstance in front of an TSA officer and manager. No information was taken and they could not have cared less. I was pretty surprised actually. Typical government, no one wanted to rock the boat.