More than likely the solvents in the paint reacted with the canopy plastic and caused the problem. I haven't had any problems here with super hot sun and temperatures, but I leave them clear. Solvents in paint can be disastrous to carbon fiber parts by the way as we had an avionics pressure vessel literally explode when tested at altitude at a firm I worked for a while ago. It had been painted with an unapproved paint that greatly weakened the structure of the enclosure.