Sleeping longer

⚜Amanda⚜ • Fearlessly formula feeding
I've had my 7 week old on a night time schedule since he was 3 1/2-4 weeks old and he usually wakes up and every 4 hours to eat at the same time every night. Tonight he slept for 7 hours, woke up for 15 minutes drink his bottle and then went back to sleep. Not sure if he's going through a growth spurt of if he knew how exhausted i was from waking up at 4 am to drop daddy off for his trip yesterday morning! Al
 Has your little one starting to sleep longer now or does each night vary? At what week did it start?