Well i doubt it. The idea of CFL's are so they can be kept on for VERY long periods of time without over-heating and blowing like normal bulbs.

It should be cool to the touch.

It might be the socket he's using, or it might be a dodgy bulb, but i highly highly highly doubt its overheating. [Well, put it this way. If it was over heating that much he'd have no plants left.]