A combination of factors at play, because trusses are designed as a big triangle, loads on one area effect all other parts of the truss, often with a snow load the center of the truss will move upward away from the interior walls. It's anybodies guess what happens with contraction and expantion do the temperature changes.
Drywall hangers that understand this don't put nails or screws to close to the wall as the wall drywall will hold up the edge of the ceiling.
So the builder should have his people remove all the screws that are within 18" of the walls.
If he dosn't beleive send him to this site.