Do stepdaughters watch their dad masturbate?

I lived with my dad as an adult woman (28). My dad would leave his door open at night. Sometimes when I walked past his door, I could hear him masturbating and moaning. It would get me so excited that I would go back to my room, leave the door open and masturbate too. I would sometimes wear revealing clothing (short shorts and tight shirts with no bra. I knew he was looking at me. I wish I had been brave enough to watch him.