I would say your fine. My son was told at 3 weeks that we can feed on demand. He often sleeps for four hours and once slept for six hours two nights ago. He is five weeks old
He normally goes to bed at 9!! Has been since he was about 3 weeks old and sleeps until around 5 and then eats and sleeps again until 8. That is why this is so weird! He normally takes a 2-2 1/2 hour nap in the afternoon with a few 30 minute naps in between each feed. He woke up at 9 and I'm putting him to bed now. We will see how this goes!
Re: 4 hour nap.... Still asleep!!
Then came a miscarriage March '11
Then came a baby in the baby carriage May 16, 12
Waiting on our second little peanut!
That would be my concern.