The VFR corridor stops at 1100 MSL, above that is controlled airspace and why he needed to switch over to Newark.
Nothing indicates he was above 1100 MSL, he was not in controlled airspace, and therefore he didn't "need" to switch over to Newark, until he was ready to call them. Certainly he would have made the switch immediately, because TEB had terminated their communication with him, but he was not "handed off", and Newark would not necessarily register his presence until he contacted them.
There is the possibility that he had reason to return to TEB, and was making a 180. In which case he would advise TEB and Newark as he returned. In the absence of a flight recorder, we could never know.