Thank you to everyone who replied to my previous post. I have a 2001 TT. There is a black plastic trim piece on the bottom of each mirror. I was annoyed by this piece on the drivers side not being properly aligned. I could push it back in place, bit after driving a bit, it would again get loose. I bought a new piece from Auto Atlanta for about $8. Here's the lowdown on install:
Hold the piece down from the distal end as you turn mirror housing inward (like when they park car at the dealer's and need to squeeze them in). The piece will basically fall off. Then push the new one on, starting at the base of the mirror. Then as you allow mirror to roll outward, push the piece upward in to the mirror body so that the tabs catch-DONE!