Not necessarily. There has been a great deal of suspicion that boxcutters were PLANTED aboard some of the hijacked planes, in the seat cushions. One of the grounded flights, in Canada, was found to have boxcutters in the overhead compartments when the plane was checked prior to being allowed to fly again.
This person may not have HAD the boxcutter at the x-ray station, but may have been passed one between the x-rays and the gate. Janitor, restaurant employee, security person, ground crew; someone with clearance who is not subjected to the same scrutiny as the passengers but is in a position to do even more damage. I'd be looking very hard at airport employees.
waiting, testing, probing.