Is it normal i like sitting behind attractive girls on the train?

I take the train to the city everyday and I always get there early, there's usually a handful of attractive young women in their 20s or early 30s sitting by themselves near the window. The train is designed so that there is one long window for every 2 seats, front and back. I search the train for attractive ladies and when I find one I think is quite attractive, I sit in the seat behind her, so that I can stare at her reflection coming off the window, and at the back of her head over the top of her seat, and sometimes if I'm lucky she will turn her head occasionally so I can catch a few glimpses of her face too through the reflection on the window. When she rubs the back of her head against the seat, I imagine that she is rubbing her head against my chest, as I gently caress her hair. Sometimes she will tilt her head up and I imagine kissing her neck slowly and seductively. Sometimes she will fall asleep while sitting there, and I imagine that she is resting her head on my thigh and feeling so comfortable around me and she is my sleeping beauty. Sometimes I even imagine what our child might look like. I always try to not make it obvious that I'm staring at her, because at times she will look into the window and suspect that someone is staring at her from the corner of her eye, and I always quickly look away whenever she thinks I am looking at her through the window reflection.