5wk old turns head to one side only

B

My 5wk old has a favorite side and only turns his head in that direction while sleeping / napping. I understand this is common in infants but could also lead to flat spots and weak neck muscles on the opposite side. We try to keep an eye on it and help rotate his head when we can.

Wondering if your newborns had a favorite side and when you started to see them rotate to the opposite side on their own.