I have seen something similar before. The edge of a laminate floor curled up along the edge of a joint in the plywood subfloor. I've also seen a floor wave like crazy over concrete, then lay down when the humidity was finally drawn out of the building. Seattle has a a fairly wet climate.. right? Anyway, You might check with some local flooring installers in your area and see if it's common in your area and what they're doing about it. If the floor is installed over a crawl space, you may be able to eliminate your problems by laying a vapor barrier on the ground under your home. You may already have a vapor barrier, sheet plastic is a good barrier but if it's already there, you may need to check for cuts or tears in the area where the problem is.