Wiggly sleeper

My son sleeps on a sleep positioner (for reflex) anyway hes recently become a wiggly sleeper and I find him off hes positioner and wiggled himself right down to the bottom of hes bassinet. The reflex is far better now so we dont need the incline anymore,

Will it be ok to remove the positioner?

I'm worried he switches over to hes stomach and gets stuck and cant breath while I'm fast asleep .....

Any thoughts? Ideas?

Hes 12 weeks.

We dont swaddle never have, he hates hes hands being covered or "trapped"