**Quote:**Receptacles Mounted on Covers. Receptacles mounted to and supported by a cover shall be held rigidly against the cover by more than one screw or shall be a device assembly or box cover listed and identified for securing by a single screw.
I might also be concerned about the way the box was secured to the surface it was mounted on.
Be sure to check for proper support.
PS: These types of raised, or flat cover mounted receptacles also require an equipment bonding jumper (green or bare) pigtail to be connected to the green screw on the receptacle, and to a threaded screw hole in the box (sheet metal screw is not permitted) or to a LISTED grounding clip. –