We bought a used 2002 28' Outback. It appears to be in good condition and we have used it several times with no problems (knock on wood). BUT it does have bubbles on the sides of the outside walls which we were told could be air/gas pockets where the insides have separated but if they are hard to the touch, they are ok and nothing to worry about, BUT if they are soft and mushy they are not. We took the seller's word on this as he also sells and owns travel trailers and motor coaches. Does anyone know if this is true? If it were leaking water would the bubbled areas be soft and mushy even slightly? Our "bubbles" are very hard to the touch and when pressed an indention can not be made or felt. We have not found any obvious leaks yet. Thanks for any input.