Well, they did do random bag checks at random subway stops for a while. It was always half-assed and you were not compelled to let them search your bag, you could just turn around and walk a few blocks to the next stop where they were not checking bags. It was all Security Theatre to make all of us here in NYC "feel safer" and let us know the NYPD was "on top of things". From a security standpoint it was absolutely pointless and people did get annoyed.