J.S.
It's totally possible but the girl is old enough to tell her father what's happening. He should just ask how she got those boo boos and be careful not to put ideas into her head about how it could have happened. If she thinks she's in trouble, she could say anything.
My son has really dry skin, just like me, and he will scratch himself raw and make it bleed, if I'm not careful to constantly cover him with lotion. He scratches his back when he's sleeping, or falling asleep. At first, he wasn't always aware that he was doing it, and then he was worried he would get in trouble, so he made up all kinds of stories about how it happened. When I calmly explained that he just has dry skin and I need his help to let me know when he's itchy, he was like, "yeah, I scratch my back ALL THE TIME." Now that I'm more vigilant about putting lotion on him after baths and whenever I notice dry skin, he doesn't even fuss at me about having to put on cream (which he used to hate).