There was a bunch of people in the train. As the seat was full, he got no choice but to stand and hold the pole near him. He keep on glancing at his watch as he running late for class.

you were at the same train as him. you didn't notice that a man next to you is looking at you, as if he intent to do 'something' towards you. Sam did notice the situation, and he find the man suspicious

he then stand next to you which you noticed, but you dont have any idea why he do that