I just got back from a 1 hr drive where I had the revs above 3k most of the time. When I got back, I found what looks to be metal in all 4 exhaust tips. It is not magnetic, but looks shiny from some angles. Does anyone have any idea what it could be? It does look similar to the stuff that collects on the bumper from driving, but that couldn't make it's way into the exhaust tips, could it?