They were not checking ID's, simply watching everyone.
There's a lot of this watching going on with the TSA. I mentioned in a thread here a couple of months ago that I caught a DHS vehicle driving around the perimeter of my property. I'm sure it's occupant was just "watching".
I'd love to know what they think they are learning from all this "watching". Me thinks,
watching = [harassment] minus [no positive impact on security]