Bill any time you spray water on balsa it loosens up the fiber, that is why it formes easier and while it also can help to straighten bowed parts drying is what causes that and it can and will do the same thing to the wing you set aside. Humidity and heat can warp most wood products including plywood, just put a piece on a table in the path of warm air and it will warp because it shrinks as it gets dryer on the exposed side versus more moisture on the other, same for your wing.

If you take your wing and put the crown side down with a 1/8" spacer in the center and properly supported to remove only the bow then enough weight on both ends of wing to force the ends down and let nature take it's course. Check it ever so often and as soon as it's straight put it some place and cover it up until your ready for it. Do that with all assembled assemblys and turn them over once in a while, keep them covered ( news paper works well ) and out of a warm air stream and avoid these problems