My son rolls onto his belly in his sleep!

Marisa • Momma to Rowan Maverick born 10-5-16 & Rhen Mason 11-28-18 💙
And it kind of freaks me out. I know it's "okay" now because he knows how to roll but I still always move him back onto his back. He tends to normally roll onto his side and sleep on his side at night but whenever he's on his tummy it freaks me right out.