I'm sorry to tell you... you have water damage.
Anytime the Luan buldges you have had water infiltration.
Push on thr bulge... then compare by pushing on an area that doesn't have a bulge... the bulge will be softer.
You can chech the skirts this way to... put your fingers insid and put your thumb outside... squeeze. The soft areas are bad.
You can sight along the sides and see the bulges... many people haven't done it... but you'll see it.
The people at Lance Customer serce showed me how... you can call them or your manufacturer.
Sorry to give you this bad news...
Sleepy