I had the same thing on mine when I got it. The dealer replaced it the first time for the rattle and it lasted about a month. Then it got so bad that it cracked the glass from vibrations. They replaced the entire moonroof frame and all and it lasted about 6 months. When I took it in about a year ago, they told me there was a recall on them. They ordered the new fixed sunroof and installed it. I have not had any problems with it since then. Tell your dealer to search for recalls. If they tell you there are none, go somewhere else.

Good luck