You didn't really pay for it and you really didnt work off your dept. While you were "working off" your debt you were collecting a salary. The only time it would be a dept is if you quit within a 2 or 3 year time frame of graduating the academy. While you were in the academy getting training you were collecting a salary also. I think it a stretch to say you paid for it.
Some posters seem to forget about that tricky salary issue related to training and "service to pay back the debt".