That's all I know. I heard it through the TEB corporate pilot grapevine.
Word is that a controller cleared the plane to land as some guys were putting the X on the runway. The pilots didn't double check the clearance, but I'm not clear on whether they could see the X or not, so that may not be their fault. Definitely a mistake on the controller's part. Sounds like it was just one guy who made the mistake at the tower. He got fired.
I don't have any sources in print to verify this. As I said, heard it though the rumor mill. The folks who told me were justthisclose to banging their heads on the wall at the stupidity of the controller.