Nighttime sleeping

Ok I'm breastfeeding on demand and my son slept 5 hours last night. He's only 4 weeks and I've only been exclusively breastfeeding for 1 week. I'm nervous that if he goes that long every night that my supply will suffer. I woke up with my breasts hard but not really painful. Am I supposed to add a pumping session at night if my baby is sleeping longer or is this fine?

I want to add that I was going to wake him up after 4 hours but I slept through the alarm. I actually had to wake him up after the 5 hours and he was sleepy at first and ended up with a lot of milk over his cheeks and neck. Lol.