I bet they were looking for a abrred rock pullet and grabbed a black sex link cockerel insteadBarred rocks do have traits that make it easier to sex at hatch, but I'm not sure if the hatcheries go off those or simply vent sex. Do you happen to have a picture of the top of it's head when you got it? The size and shape of the head spot help determine male and female on pure bred barred rocks. Then again, a black sex link male would look identical to a pure barred rock hen at that stage.
I don't have an individual picture but this was when they were all two days old.
