I *think* what you may be talking about is "vinyl trim insert". It doesn't say in your post what year your TM is, but I know they used it in the older ones because mine has it and we replaced it because it was stiff and yucky looking. It comes in different widths and colors:
http://www.campingworld.com/shopping...rt-strips/1616
I think it would be a good idea to replace it, yes. Any extra insurance against water intrusion...