From what I've heard from the guys at Boeing (formerly ASTA formerly GAF) who were over here testing the flap mod, that the army did work them hard and did a lot of things that civilian Nomads would not be subjected to (sounds fairly typical for most military aircraft). But the problem with the flutter of the aileron/flap system was just slop developing through the clever system for the aileron/spoiler set up. But the new mod has stiffened that up considerably - to the point where at full flap instead of the flaps being blown back to 34 degrees in flight, they are only blown back to 36 degrees.
If only the N24s had the same infinite flap settings as on the N22.