3 month old likes sleeping on side/stomach

I’ve noticed lately my 3 month old likes sleeping on his side/stomach more than his back. We always put him to sleep on his back but he usually ends up turning to sleep on his side or stomach. I’m wondering if anyone else’s baby is like this? If so do you let them stay sleeping that way and is it okay?We put him back on his back but he’s able to roll from his back to his belly and from his belly to his back so sometimes he just turns when we’re sleeping.