I am looking at a two story house where the drywall compound over the ceiling nail fasteners has poped out of the drywall approximately 1/4". It is not what I would consider a classic nail pop. I removed the poped drywall compound from a couple of the fastener areas and found that the nail head is recessed about 1/4 ". The nail has rust on it and the piece of the drywall compound has rust on it. The 9 year old ceiling/roof constrction consists of wood trusses at 2 o. c. , 5/8" drywall, and blown-in fiberglass insulation without a vapor barrier. This fastener condition is ocurring within 3" on a non-load hallway bearing wallnear the center of the 2nd floor. There are a few other spots on the opposite hallway wall. There are a few hairline cracks and tape failures along the wall/ceiling joint. Looking in the attic, I can see that the top of the drywall is raised up at the location of one of the nails. At the location checked, it does not appear that the bottom chrd of the truss was nailed to the top of the partition wall. Although this is not a classic case of truss uplift(partition separation), my thinking is that this is truss uplift related. The depth on the nails into the drywall may also be a factor since the drywall paper would have been broken. Maybe these fasteners were previously repaired and the nails driven deeper into the dry wall. Could the rust on the nail head have pushed out the thicken drywall compound over the nail? Does anyone have any other thoughts of the cause of this type failure?