This may sound odd, but I was wondering if you guys had the same thing happen to you. Down by your shifter you may notice there are some plastic pieces that slide back and forth when you shift into gear. Mine slides forward and back when I slow down for a light and/or take off from one. I usually listen to talk radio, so it might be a little more pronounced with my car since I'm not jammin' out all the time.
Have you guys noticed this with your cars? If so, do you know of any way to keep it from making any noise?