This seems like a pattern developing. Either you've been pretty unlucky or something about you or your commute is causing these things to happen. Maybe a combination of luck, unfamiliarity with subway etiquette, and thin skin.
As LegendKiller advises, don't yell at or talk back to anyone. Just go about your business. Keep your head down and your nose clean.
NYC is much less tough than it was 10-15 years ago, but getting ready to "throw down" over a shove seems like a good way to get into trouble.