As most carbon fiber of high quality is autoclaved to remove trapped air with a vacuum pump and heat, an air bubble could be underlying structural issue. ie. an air pocket. Without resin carbon fiber is just fabric. You might should investigate this. Frame replacement by the manufacturer may be in order. I have some 5 years experience as an industrial painter and we used to powder coat carbon items. Not a common procedure, but the inclusions of air in an object show themselves when heat is applied to cure powder coating. The air within a pocket expands and blows a bubble in the finish. - Wes