I wondered about that too, but it never said if they calibrated the refractometers before using them. If that refractometer hadnt been calibrated, it could very easily give a wrong reading, which is what I suspect because all the others read dead on.
And I think it good that they did the tests with expired kits, because that is probably what most of us are using.
I honestly dont test anything but alk and my salinity now, and I do double check my alk results against the store's results. If I have other issues, ill see it before a test kit can pick it up.