Vibration from air diffuser on 2013 SHO

[jag8723]

I haven't gotten a chance to go to the dealer yet but when I drive with the moonroof open the air diffuser starts vibrating and shakes the headliner. It seems like it only happens around 60-65 mph. Does this happen to anyone else or does it seem like their is something wrong with it. I just bought it Saturday and so far I am loving the SHO it's almost as fast as the tuned BMW 335 I had but rides so much better.

Thanks for any help!