I too have noticed this on occasion, with over 21,000 miles on the odometer. I found if I stop the car while in reverse and let it sit a second, and then shift into drive, it does not do it. I was going to take it in to the dealer, but I am going to wait to see if it gets worse. I prefer not having anyone open the transmission unless it is a serious problem. Let us know if you see a continuing problem, getting worse, or if the other gears start doing the same thing. I am going to check the MB forum to see if they have a history of this or a related problem.