GM had that exact problem when they first introduced base/clear on their production vehicles. There was a sizable recall, especially on blue vehicles, due to the clear blistering and flaking off. I've also seen my fair share of aftermarket base/clear paint jobs, done by both ameture apinters and professional body shops, with that problem. Prepwork is vital on any base/clear (well, any paint system really), as the clear will only be as good as what's under it.
