"The sleeper cells are assembling"
That was my first thought.
That was my first thought.
Mine too.
The sleepers are already here, the ones coming in now are brining the alarm clocks.
Remember those students who went missing awhile back? How many were there, 10 or so (memory fading..50 next month), did not show up for classes at college. They were found, in ones and twos all over the place
Delivering messages, IMO.