Kind of throws me as the bonnet is in two parts and are popped in a spray booth with the wings ( depending on size ) but without the mog body, placed on somthing or hung and sprayed away from the mog ?!!!!!!.
No the whole car apart from the rear body panel was sprayed at the same time.
Only thing I can think of is that the car is garaged over winter and covered with a tarp over the top only.
Could be the bonnet holds condensation, whereas the rest is open to dry out, and has absorbed moisture.
Regards, Geoff