is this assault?

i was on the train and a man tried to get closer and closer to me but at first i thought i was imagining it because the train car was crowded but every time i looked down it seemed as if his hand was getting closer and closer to me down there and i was freaking out and i moved to the side but a few seconds later it seemed as if he was even closer and he seemed to be smiling as he was doing this.why me? i don't understand i always go through all of these things but what have i done to deserve any of this.