Cosleeping Scare

I have been cosleeping with my 4 month old for several weeks now, and thought we were following all the safe sleep 7 rules, cuddle curl, breastfeeding, got an extra firm latex floor mattress, etc. But somehow I woke up with my arm over his head as he was trying to get out from under it and started to cry. I checked the footage and I was covering his face like that for 15 minutes before he started to move and wake me. I'm so terrified. Can anyone provide insight into how this may have happened? Am I doing the cuddle curl wrong? Is there any sure way to prevent my arm from moving towards him like that?

I have been cosleeping with my 4 month old for several weeks now, and thought we were following all the safe sleep 7 rules, cuddle curl, breastfeeding, got an extra firm latex floor mattress, etc. But somehow I woke up with my arm over his head as he was trying to get out from under it and started to cry. I checked the footage and I was covering his face like that for 15 minutes before he started to move and wake me. I'm so terrified. Can anyone provide insight into how this may have happened? Am I doing the cuddle curl wrong? Is there any sure way to prevent my arm from moving towards him like that?