Bill,
Lots of good educational info on truss uplift, but here are some suggestions if and when you go back to inspect the home (to help out the homeowners/clients with their problem).
1. Check attic for proper levels of insulation and most importantly check for uniformity (12 - 16 inches evenly distributed).
2. Make sure the attic is properly ventillated (are there air baffles in the soffit vents? ridge vent or pot vents OK?)
3. If all this looks OK, then suggest additional fasteners be installed in the trusses particularly into the top plate of all interior walls.

Hope this helps,
Bob Dalga
Home Analysts, Inc.
Kalamazoo, MI