Yes, on a Yamaha XS1100 many years ago. Header was too close to the stock cooler line, which was wrapped with nylon, not metal, mesh. Melted the wrapping, then a stone off the road took out the rubber inner tube that was bulging through the hole.
Got oil all over my boot, which was my first clue that something was wrong. Had to trailer the bike home and get a replacement cooler assembly as I couldn't undo the tubes on the old one without damaging it.