Can we get some pictures or details on his vivarium? 2 Feet sounds perfectly fine for a snake his size - in fact, it may be a little too big and causing him to feel insecure. I agree about larger prey.
They don't hold grudges so I would look at other factors. This forum is great and I've been on several others... this is the only one I'll actively participate in because every hobby has elitists and those elitists like to gravitate toward forums to feel powerful and important. This one managed to attract the people who just like to be helpful and discuss the hobby!