That ain't rust. You should come to the Gulf Coast and check out some of the folks that live on Galveston Island. 1-2 years out there and I can take a hammer and knock chunks of rust scale off. Besides if you go to your dealer freaking about mere surface rust they will never take you serious again. On the other topic if the click occurs on initial take off or when shifting from forward to reverse of vise versa. There is a bulletin for the older coupes about removal, cleaning and lubing the splines on the rear half shafts. I think it also applies to the G37 but not certain.