rolling on tummy in bed

Hi mums! My little girl has been rolling for ages but she has always kept it to day time hours which is great! Over the last few days she has started to do it in her cot & even sits bolt up right whilst asleep. Sometimes she will just go right back off to sleep but sometimes when she rolls onto her tummy she wakes up & it takes a while to get her back off. Anyone had this & what's the best thing to do in your experience? She has always been put to bed on her back & she normally rolls onto her left side..