I think you are right. I was doing that originally, and I think that's why I am noticing this "change" in the appearance.
On ProE 2001, I don't recall them having a view manager, so you'd have to do an assembly cut to view the cross section if you didn't want to do it through a drawing.
I think when I finally discovered the view manager in creo, I didn't notice that it messed up texture maps. After these years I must have "thought" I always used the view manager for this project, when in fact I didn't.
That's extremely lame though, because in the end, a defined color is not much different from a texture map. Clearly, there is a very obvious work around that is in some ways more flexible than the view manager itself.