Baby covering face with hand during night

Anyone else’s little kinda make you nervous during the night? My babe is 5 months and began belly sleeping around 4ish months (makes me nervous alone but I knew it was going to happen sooner or later.) She started sucking on her thumb to fall asleep / self soothe but I notice when I check on her throughout the night there’s times she kind of covers her nose in the process of that which makes me nervous with her breathing okay. Is this normal? She would move it if she couldn’t breathe correctly, right?