During the manufacturing process, the glue used to secure the roofing material to the plywood underlayment goes through a “curing” process. In some instances, the glue continues to “cure” after the roof material is in place and the gas causes an air pocket. Typically, they will never get any larger and do not pose any threat for leakage or structural problems. If your unit has one that is making you uncomfortable, have your dealer check it for your piece of mind.