I also ride in NYC and use puncture resistant tires and I get maybe one flat a year if even. I had a really bad luck in March though, I had three flats in one month! But as always, the first flat was caused by a legit reason and the remaining two by stupidity: I didn't examine the tire well, and there was a tiny piece of hair-thin wire in the tire that caused the following two slow-leak flats.

Also, the flats seem to more likely to happen on lousy, wet and cold days