Is it normal to masturbate while sick and naked in bed?

This was when I was 15. My family and I went to our friends house to visit and help them because basically their whole family had fell ill, except for the dad. They have a very hot daughter who was in my class. She was in bed when I walked into her room, completely under her blanket. I could hear soft whimpers and moans coming from her, and I thought it was because she was sick, but when I lifted up her blanket a little, I realized that she was not wearing any clothing at all, and she was fingering herself with one hand, while pinching her nipple with the other.