Was the incomplete set sealed when you received it?
it looked sealed but the side proto label had lost all its stickiness on one side of the clamshell case and was a false positive for "sealed". The top barcode label was scrunched up but i figured that could have been done in shipping when i first grabbed it.
just saw your post that you were missing a piece from the set. Maybe Grainger was trying to unload their defect inventory at 31$