Pretty sure I heard/walked in on my stepdaughter masterbating

So this happened about a week ago. It’s winter break so she has been home more. I can’t remember what I needed her for, but I went to get her. I knocked. I knocked again. Nothing. So I cracked the door open and open it slowly. I see that it’s dark. No lights on. But I hear her panting, breathing heavily. I called her name. She responded as if I interrupted something. She hesitated, says “yes?” Maybe I was telling her dinner was ready. She she said ok. So I either caught her climax or she just woke up from an odd dream. 😂

On a side, I did see her topless (finally) maybe two days before that. She was changing her shirt with the door wide open. I walked by and passed it. Wide clear view, I saw her sweet beautiful 18 year old tits. She yelled! I told her, why are you changing with the door wide open??

This winter break has been great.