I checked the carfax before I bought it and everything checked out. No reported accidents.
First time I noticed this was when I lifted my butt up to get my wallet out of my back pocket. I heard the seat pop. This action probably puts some stress on the back of the seat and forward bolts. I do this pretty often too, because I always forget to take my wallet out of my pocket. Some of the rough roads I've been on in the past few months probably haven't helped either. Saline Valley Rd in Death Valley was pretty rough.