Then I don't understand your confusion.
If your normal stride is 3ft and you calibrate your pedometer to that, then when you're in the queue let's say your average stride is 1ft and every time the line moves you take 20 steps, the pedometer will read that as 60ft. When, in reality, you only moved 20 ft.
Now, I'm admittedly terrible at math, but even I can figure out that that is going to throw your "mileage" off pretty badly.

