See it all the time doing forensic work. This is my standard paragraph, and have seen similar in other's reports. You can google this and get similar info. At the top of the wall is very common since sometimes they will use a couple of nails to temporarily secure the gypsum board. They should probably remove them after they screw, but they obviously don't...
Nail pops are commonly attributed to shrinkage stresses of the wood framing that push the nail out of the lumber, causing the head of the fastener to “pop” or protrude away from the surface of the paper face of the gypsum board. A longer nail shank will exacerbate this phenomenon. Screws and ring shank nails offer more withdrawal resistance, and are less likely to be problematic. In the case of ceilings, when too few fasteners are used to attach the gypsum board to the ceiling framing, the weight of the gypsum board may cause the fastener head to slightly crush the gypsum, causing a slight indentation. Other workmanship and material issues may also be exacerbating factors in these surface imperfections. Nail pops are not an indication of slab or foundation movements, and are considered minor cosmetic distress.