I thought for sure you were going to say you just put shag carpet on the roof of your X.
You know, I had the same thing happen on my old Malibu and I ended up cleaning the whole roof so that it would all be the same color. I smoked alot in that car so I think that had something to do w/ the big difference when cleaned.
It wasn't the same color as the X but similar. There may be a better solution but it worked out fine for me, kinda liked the new look actually.