My son who is 15 weeks, slept at 12 midnight last night slept u til 8 am. Woke up drank milk stayed…

My son who is 15 weeks, slept at 12 midnight last night slept u til 8 am. Woke up drank milk stayed up until 11 slept until 1 went back to sleep in the car after his bottle at 130 which was around 245/3 then slept until 6 had another 6 oz and has been sleeping until now it's 9 o clock. He woke up for a few minutes here and there. He hasn't slept like this in a while is not sick?! Should I be worried? Maybe it's a growth spurt?