If the roof is made of plywood, there could be a knot hole under you rubber material. If you go to a hardware store and look at a sheet of plywood, especially cheap stuff, you'll notice that there are pock marks, knot holes in the sheet. These are actually limb holes. If you understand how plywood is made you'll onow what I'm talking about. If the edges of the pivot are solid and not soft, I wouldn't worry. I certainly wouldn't walk on this area as you may cut into the rubber roof with the sharp edges of the plywood hole. Kind of like a biscuit cutter from underneath.