1 out of 4 bolts missing, it is quality issue. If 2 out of 4 bolts missing, maybe it is big quality issue. If ALL 4 bolts missing, it is a sabotage. If you understand airplane installation and parts distribution procedure (the parts department only issues the tools and number of parts needed for the task), when the install worker with hand full of extra bolts after completing his task, he just didn't forget to installing it. I hope FBI involve in investigation. I don't believe repeated error and omits. It is NOT hard at all to find who/the worker was responsible to install this door panel. I suspect there are enemies within Boeing.