Thanks all for your comments. Yes, I do use a stop, so as I suspected it looks like it's probably just water doing the streaking. But Ed, it was hot enough in there yesterday for me to do the streaking too. I usually just use a wad of paper towels, but I leave one end on the drum, so the water probably originates from that end. I may try using a second drum to give each one time to dry. Again, thanks all.