I have a system six one of the ones that is half black half polished. Anyway I picked the bike up the other night and I could hear something rattling around in the frame. I took the fork off and shock the frame and out came what looked like a tiny rivet head, about the size of a nail. Also when I had the fork out it looked like there was some carbon shavings in the headtube. They looked like they were coming from the carbon overlays behind the cable stops at the top of the down tube. The carbon inside just looked messy. Should I be worried?

Thanks

It's not uncommon, from my experience, to have things rattling around inside cannondales that are multiple material compositions. Ususally I've seen what appears to be light yellow or cream colored dried epoxy debris. The rivit head might be a bit concerning as a cable stop or similar, but not likely a tubing junction as these are held together by glue.

Thanks for the answer