Just a suggestion...if he keeps waking up at the same time every night and he's not hungry, you may want to try Tracy's "wake to sleep" technique. I was just reading about this in the book, so I can quote you exactly what Tracy says:
"set your clock and hour earlier than your baby usually wakes and go into his room. Jostle him gently, rub his belly a bit, and stick a pacifier in his mouth - all of which will help stir him to semi-consciousness. Then leave. He'll fall back asleep. This gives you control, rather than your sitting around hoping that your baby's habit will magically go away. (It won't.) By waking him an hour early, you'll disrupt his pattern."
I am about to try this with my son, who keeps waking up at 3:30 every morning and will go back to sleep as soon as he gets a pacifier. So I don't have any personal experience regarding whether this technique works or not. But good luck and let us know how you're doing.