Or is it possibly the door seal?  I believe some people are having
this problem.  Not sure of the fix but think it could be silicone
lubricant applied to the seal.

Here's a great TL site to search/join for lots of info and very
helpful members:
http://tl.acurazine.com

Could this be the problem?
http://tl.acurazine.com/forums/showthread.php?t=84527

I think I would try some of the new spray wax/polishes that can be
applied to rubber (does not turn white) before trying silicone that
might end up on a painted surface.  I had a bad experience spraying
silicone lubricant on a noisy lower dash panel (1979 Sunbird).  As
excess silicone ran down the outside of the panel it took the paint
off.  It was close to the door jamb so my paint touch was not very
noticeable.

I would guess there is probably a product made just to keep rubber
seals in good condition.

Good luck and let us know when and how you solve the problem.