that is delam caused by either a bad layup from the factrory and high temps will cause this over time also the delam can be due to water damage. I work in aerospace and see this type of stuff on ocassion. a bad bond detween the layers of material or not enough time in the autoclave to bake out any trapped air or moisture will cause this. Water is usually the culprit if the layup was good from the factory. look for a leak that is allowing the moisture in.
Dan, Kelly and Maddy.
Cupid and Kandi the Camp Dogs
2006 Salem LE2013 Ford F150 Ecoboost Supercrew w/ factory tow package