Sleeping through or ill?

My boy is 9 weeks old and has always fed every 3 hours from birth really - night times he sometimes stretches to 4-5 hours. We’ve suffered with mild colic and usually takes a while to settle him or cramps will suddenly awake him.

Today he fed at 8pm and he dozed off but not fully asleep and he eventually went to sleep at 11ish (which I thought was unusual as his 3 hours means he should of been having a bottle) but then we fell asleep and he didn’t wake me up until 5am.

Should I be worried? Ive took his temperature and its 36.4 and he fed ok (bit of reflux as usual) and he’s just kicked around for 15 minutes then gone back to sleep.

Is it normal to suddenly sleep that long? I’m always conscious that not feeding often is a sign of illness