I have about 1800 miles on my Touring. Starting at about 1000 miles I hear a rattle from the sunroof area at certain RPMs or road surfaces. Opening/closing the shade has no effect. I am able to get it to go away by slightly lowering the passenger-side rear window. Not much, just the minimum you can lower it with the switch. Superficial inspection of the sunroof doesn't reveal anything to me, (except a lot of whitish lube around the edges of the track) Anyone else hearing this? Any ideas of what it could be?