The deck of my kayak was fiber glassed inside and out but before I could fasten it to the hall it rolled or curled up badly. I had to streach it out under lots of pressure with stick spreaders to match the hall. The deck actually buckled and cracked along several thin strips and the white pimple dots formed all over the deck, which is a partial delamination. I am sanding them out now with 80 grit paper. When I tried to sand them out with 120 grit paper more dots form around the sanding area which was very hot from dull paper. So it looks like stress and heat will form the pimples.

John