Making him wait was probably the cruelest thing the Master could do to him. While the responses made him feel sick, the silence left him feeling alone and vulnerable. For all he knew, Valek would return at any moment and decide just to drain him of all his blood.
The Doctor furrowed his brow in confusion as the Masters voice drifted back to him. Martha? He hadn't even been aware of her presence in L.A. Don't you think you've given her enough hassle for one lifetime? Of course, he knew the answer would be a negative.