I think it's those areas that have stress/ tension from weight combined with moisture build up in the glue between the two interfaces of bead board and fiberglass, combined with age and road flex. Although 'Road flex' would be a good name for a camper....... they are supposed to take that sort of continual use.
Other problems I've read about the bead board came apart. In each case they have all been able to be repaired.
My bulge did not show until I used it continually in winter. Never had this problem for 13 yrs prior.
