This doesn't make sense, nearly all the sources I have say that the F-22 only has RAM applied to it's leading edges and other critical areas, it seems strange that it would be covering the entire underside of the plane. From your description it sounds more like maintnence on the deeply buried engines of the F-117.
it does make sence. after all i would consider the belly of a aircraft critical area since most radar is on the ground and the plane would be above it. coarse it doesn't mean they already revised the design to fix any flaws.