Is it normal for your sister to jack you off?

I was 14 at the time and my sister was 16. Out rooms were practically right next to each other and she would just come in once in awhile without knocking, even If my door was completely shut. It was late at night and me being a teen I would jerk off once in a while. I forgot to lock my door and I didn't think much of it, I mean it was 10:30pm I thought she was asleep. So I was propped up against my pillows stroking it when my door suddenly opened, I was scared shitless. I thought it was my mom at first. I hurried up and went under the covers but it was too late my sister had caught me. She stood in the doorway shocked, but then she had this sudden urge look. Without saying a word she closed my door, locked it, and started walking towards me, she sat on my bed and just grabbed my dick. She slowly started stroking it then she picked up the tempo and as she did, she had the tip of her tongue on the tip of my dick. She was teasing it. It didn't take her that long to make me cum , some of it was on her tongue but most of it was on her hands. But the whole time I was thinking why would she do something like that? So all I'm asking is, is that normal?