I have an '03 EXT and the semi-hard plastic gasket around the rear window just cracked apart at one of the bottom corners, it has pulled apart nearly 1 inch. I noticed it cracking a couple of months ago and now it's completely split - inside & outside. Has anyone else had this happen? Does anyone know if a new gasket is available or do I have to get an all new back window??? I already checked GM Parts Direct and didn't see any replacement gaskets. Please post if you have experienced this before or have any information in this area - Thanks!