The griffin knew that the mouse was blind, and thus had no idea that he was having tea with an enormous monster that, despite the foreparts of a dodo, nevertheless posessed a carnivorous feline stomach. But it's lonely being a monster, particularly when your front half is extinct, and so he pretended to be a much smaller creature, and drank tea very cautiously out of the mouse-sized teacups, and kept his voice down to a whisper whenever he visited the mouse. The mouse was, indeed, blind (being descended from one of a moderately famous trio) but was also nobody's fool, and there was absolutely nothing wrong with his hearing. The griffin's breathing couldn't come from anything smaller than a bull elk. He occasionally wondered if he should offer his guest a bigger teacup (or possibly a barrel) but figured that if the griffin wasn't going to say anything about it, neither was he.