I would imagine that the rate the x11 contracts where picked up that users probably have purchased close to the limit of the capacity that genesis-mining had initially planned for. Perhaps they were surprised by the demand for it. Thus i think they are near to their capacity and probably decided to limit the purchases to allow all users to avail of some x11. So i would imagine in a short time the x11 contracts wont be available for another period of time. Just my thoughts on it, could be something else of course.