I'm a Canadian NEXUS holder, and I landed at Atlanta airport earlier this morning on a Delta flight. Exiting from the plane, the security (or an airport worker) guided me to an exit through the hall. I ended up at the airport train platform. I got in the train and got off at the international baggage claim area, and then exited the airport without any problem. I was not aware that this is strange until my friend told me that it's abnormal and might get me into a big trouble. Should I call the airport or TSA, or does this happen normally (or at least from time to time?)
I flew from Toronto Pearson Airport and scanned my passport and answered several questions on the NEXUS kiosk (including the address I will be staying); I guess it was pre-clearing. But how did the security know if I already pre-cleared at Toronto airport and opened up the door to separate hallway?