Not sure how I should have reacted

The work day ended well at 9PM when my professor ended the class 30-60 minutes early (it's a 7:30-10PM class that he usually dismisses at 9:30, but today was 30 minutes more special).

I ran to the subway station, missed the train by no more than 7 seconds, as the doors closed while I struggled to get the metrocard out of my pocket. I took advantage of this fact by going to the nadal 1 deli to pick up a delicious chicken philly cheese steak. So good.

Upon my return to the underground, I went through the turnstile and another person went after me, but I am pretty sure he didn't pay - somehow he just slid through it. I watched this with curiosity, wondering if I could do it as slickly as he. Noticing me, and perhaps thinking I was judging him, he let out an aggressive "what are you looking at?"

Not exactly afraid, as this was a public place and this stranger seemed to be around 15, I was nonetheless startled. In such cases, the easiest reaction is "nothing", which is what I said. If i did it over again I might have commented on his inventiveness (it looks more legit than the usual jumping over the turnstile) and that I was pondering implementing it myself. However, I wasn't sure if he was seriously upset so I decided not to confront him.

To my surprise, there was an even younger kid (I would guess no more than 12 - he looked small but sounded mature) who told the "aggressor" not to be a jerk, and walked over to me, shook my hand (in that cool way, not the boring business hand shake) and told me that guy was just kidding. I said "thanks"... and maybe an "it's ok", not because I was upset by the situation, in fact I was genuinely pleased that this occurred because it just reaffirms that New Yorkers are really nice people. So the kid apologized for the older kid, then another girl apologized for him, then as I was walking away towards a more strategic location on the platform (for the exit at my stop, not to distance myself from them) the "aggressor" chased me down and apologized. I was super amused and pleased. I couldn't tell if it was an offended look on my face, or if they thought I was going to cry, but basically at least three people took the effort to make me feel better and it felt great.

Turns out they got off at the same stop as I (coincidence? ..well, clearly, but it is a cool one), and it turns out (naturally) that they live a couple of blocks away and the younger kid's name is Michael and he goes to school in the area and he said "cool, I made a new friend". Unfortunately we didn't get into the subtleties of defining friendship, but it was just nice that my expectations [accumulated over my first year of teaching] that all young kids are a-holes are finally starting to break down.