Babies should nurse when they are hungry and that will vary from baby to baby. Also you may notice an increase in feedings every 7 weeks or so when they experience a growth spurt. Usually growth spurts are also accompanied by more sleeping. This is completely normal. I agree that you should watch the queues, if he just want to nurse to fall asleep then he wasn't really hungry. It's a constant learning experience because just when you think you've figured it out, the baby changes the rules. The good news is as he grows he will sleep more hours at night eventually!
You also want to make sure you are not picking him up right away when he wakes up. Let him fuss a bit. He is getting to the age where he will need to learn how to comfort himself back to sleep. If after a few minutes he is still fussing then go and see if he is hungry. I agree to feed him first, then put him right back down to sleep. The more you sing, rock, pat etc the more he will want to wake up just for that!
Enjoy it while it lasts!