More likely, they're checking how many are leaving, though it's not an exact science given they claim it was just a 'copying over error', now known as a 'bug', but refuse to 'correct' it.
STILL not corrected!!?? Yikes. Queue ominous music...
Yeah it did cross my mind that soon they could say "Right, well you've had your 30 days notice of the royalty rate change as required in the ASA. The new rates are now in force".
But a little bit dastardly though they can sometimes be, I would't think iStock would be as Mr Burns-ish as that!