I have a 2006 f150 with rail caps on both rails and the tail gate. I recently bought a truxport tonneau cover. My question: is the 1" rubber flap on the tailgate end of the cover supposed to go inside or outside (rest on top of the tailgate) of the tailgate? Mine is inside and I don't get any leaks, but I wonder if the tailgate closing on it will eventually rip it.