Tomorrow we are having carpets fitted so I moved the sofa out of the way to have a clean behind it and it backs onto a radiator. At the bottom of the radiator there was some green dust (?!) or crumbs on the floor and around the pipe. I cleaned this off with a sponge and dried it and there doesn’t seem to be any leaking. Do I need to get it looked at? I always assumed something like that would mean a leak! 