Arb after dark?

I go to the arb at night to smoke all the time, but tonight when I was walking in some people came out and said that some guy was walking around the arb telling people you cant be there after dark? at like 10pm?? anyone know anythin about this? I've seen on the google page for the arb that it "closes" at 6 but I've never heard of it being enforced and the people said it was just some random guy telling them that he would call the cops?