Mitsubishi is famous for that trait in their cars...yes that is normal. I have no idea why they do that, but what I did was go to a fabric store and buy some headliner material. Fabric stores actually carry the same material that is used in your car now. Just ask the people at the store where the headliner material is. While you are there pick yourself up some 3M spray adhesive and you are good to go. I did mine black like 3 years ago and it still looks great.

here is a link to a write up as well... http://forums.2gnt.com/dcboard.php?az=show_topic&forum=7&topic_id=35418&mesg_id=35418&listing_type=search

Hope this helps!