A friend of mine has a couple of “warranty” frames. Frames which were returned to the manufacturer as faulty (lacquer issues) but which basically are fine. The manufacturer replaced the customers frame with a 100% one but the old returns were sold off at trade to staff, family etc.
Bottom line is they were fine bar minor cosmetic issues, no point in perfectly good carbon fibre being used as landfill.
It’d be worth checking with Specialized, give them the frame number and make sure it wasn’t part of a stolen batch or warranty. The guy might be legit (maybe staff?) or he may have got hold of a load of stolen or sub-standard frames…