I no longer have my K-70 box, but neither my KP nor my K-3iii were in sealed boxes from Bristol Cameras, neither do I remember screen protection, but I may be wrong on that..
For less than a couple of dozen shots I'd have thought it was unlikely to have been a return, more likely an on-counter demo or even a salesman checking it worked before dispatching it. Rather clumsy not to have wiped the screen and re-packed it properly!
I'd have thought worth at least a complaint in writing, you might be able to scrounge a spare battery or SD card even if they don't offer cash discount. At least you'd have officially registered the fact, so, in the event of something else turning up, they can't say you didn't tell them at once