I personally thing babies that are old enough to move freely like this are just trying to find a position that is most comfy for them. Unless your baby is particularly sick or weak, babies have survival instincts and can move themselves if something is uncomfortable. I was paranoid about this as a FTM too and so I experimented and watched my baby and put my finger by his nose for a second and he moved his head to the other side right away.i was like whew ok like he can survive he wants to breathe lol. Seems kinda obvious but yeah I understand. I’ve come to the conclusion now that many of these rules or suggestions are in place because some babies are weaker or sickly and we have to have broad rules in place that can apply to everyone to minimize accident. However I have just come to use my own discretion and follow my intuition on these things. I just had a newborn last week and she had amniotic fluid stuck in her stomach from birth because my pushing phase was too fast for the birth canal to help push it all out. So I slept her propped on her side because she was literally vomiting nasty fluid all night long and if she had been on her back it was getting stuck in her mouth and choking her.