Today I used GE for the third time, all through T8 (aa) at JFK. The first two times, after getting my p/o from the GE terminal, I proceeded to the exit (I don't check luggage), the agent took my slip and said to go through to the final exit. Today, after handing the CBP agent my slip, he looked at it and
looked at something on his desk and then told me to just go through, but his tone was more like he was doing me a "favor". It only took 30 seconds extra. Is it possible he is new and has never seen a GE slip? [Also, my flight from ZRH arrived at the tail end of a flight from somewhere in Central or South America (one could see this from the pax

) and maybe he didn't expect pax from my flight to get to the last step in the CBP area so soon.)
CBP verifies the validity of your receipt with a check digit that is changed several times during the day.