Sleeping on his side

KMZ1983

We brought home our baby last week after 11 days in the nursery. Immediately he started sobbing if we swaddled him at night. Honestly, I think he is just tired of having his arms down all the time since the nursery swaddled him 24/7. We decided to just outfit him in a warm sleeper (our house is set over 76 degrees) and a hat. He sleeps well, but I've noticed that when I check on him throughout the night he sometimes kicks his legs so he is sleeping on his side.

I know they say to always place babies on their back, which we do, but he positions himself on his side (and will roll back to his back on his own). A friend of mine mentioned a positioner in the crib to keep him from rolling, but it makes me nervous that this could be a suffocation/SIDS risk.

I'm a FTM and never thought about my newborn rolling to his side. Any advice from others?