In that chapter I got the feeling that Miranda's point (or something...) was to mention the 'Stark bastard' before Alayne and see what her reaction will be. What is the chance of some random bastard girl raised in the Free Cities to know the name of some bastard boy raised in Winterfell? Zero. That is if the girl really is what she is trying to look like. Actually, the moment Sansa asked Miranda if it was Jon Snow she was talking about was the moment when the whole 'Sansa is getting smarter' was destroyed for me. She allowed herself to make a mistake that significant. Again. And I'm only waiting to see how badly will that effect Littlefinger's schemes.