I to had electrolysis on a small area above the "wings" on my 93 Lance. When I took it all apart to fix I noticed that a steel staple had touched the aluminum panel along with the moisture started this action. It actually had created several pin holes. I would be a little concerned about this in a fairly new camper. (Mine at the time was about 17 yrs old). I repaired everything properly & still use it today.
As mentioned earlier it could be "stray current" (pinched wire) somewhere, but does have to have moisture to start this process. IMHO Good Luck