Newborn moving head side to side.

Hi mommies, my baby girl is currently 7 weeks and 2 days old. She’s a very gassy baby, so I place her on her tummy during nap time. However, recently she’s been moving her head side to side while being asleep (on her tummy) and that has worried me. Also, she would always soundly sleep on my chest after feedings and now she keeps moving head side to side before fully falling asleep. I read some similar reports online, but none of them mention being on their tummies. Should I be worried?

Keep in mind that she does not cry or complain during these head movements and has always slept best when placed on her tummy and I never leave her unattended.