Could the calibration of my speedometer be wrong?

I have a 1995 Geo Prizm and its a great car. However I’ve noticed that I get passed A LOT, especially when I’m in New York for my horseback riding lessons. As a disclaimer, I’m honestly not a bad driver at all- and I know that especially in New York it’s better to go a little over the speed limit because they get really pissy really fast. So anyways, yesterday on my way home, these old people passed me and crossed the double yellow lines all while beeping the horn and making faces at me. I was going 43 in a 35. What gives? Could my speedometer be off, or were they just typical New York assholes?