The panel is made of nonmetal compound materials and is part of the base of the right wing.
Explains why it isnt bent....
Lets assume this aircraft was assembled first, then painted. Also assume that if it was a lapped piece, (underneath another) the paint would reflect this.
I do no notice any paint circle of base primer that would indicate fasteners missing. I would think that if it was fastened, then painted, removing the fasteners would leave a ring of base primer. Looking at the image, it appears that some of the holes are painted.
If a piece was lapped, again underneath would prevent paint of the lapped section, and would be evident.
What I note in this portion of the panel, is full paint, and no fastener holes at all.
