Well, if she would like to learn, rather than just saying it to humor or encourage him, then Inigo knows he can't pass up on this.

.. though he is thinking for a moment.

"Maybe it's better to start on that some other time then? You know, so I have time to prepare.." You'd think he has to prepare the instructions, but no, he just has to prepare his heart. From the inevitable shyness. Go figure.