I know we had talked before about your car, and I dont remember if you said single stage or base/clear was going on.
Single stage is really hard to fuck up, unless you have another chemical inbetween coats like Mike suggested.
Base/clear over top of single stage will lift once you get to the later base coat, and into the clear.
I know you had the quarters done and some other things fixed, leading me to believe all of this was in primer. Where all the primer was layed out he shouldnt have had an issue...unless going back to Mikes statement.
Was this just across the top of the car? You said it happened in the strips. Is he laying down two types of paint?
Is he putting single stage stripes over uncured clear?
Really there are a few variables that come into play. And not knowing all of the information, its impossible to come to a solid conclusion. Dirt wont make the paint bubble, water in the line wont make it bubble. Silicone can make it fish eye. Number 1 reason I dont use silicon tire shine. Anyone who paints cars should know, only silicone free chemicals in the shop.
Bubbles are common of a chemical reaction. He must likely mixing incompatible chemicals or rushing by not allowing appropriate time for each layer to flash.
If he's fixing it, thats all that matters.