Does Nora the piano playing cat have an aptitude for music like we do?

Hard to say. Cats are also known to paint and their paintings are actually quite aesthetic... although they aren't given a full pallette to choose from. There is a book written on it. I think Nora is just in love with what she hears. And who knows how it is interpreted through her ears. It is unlikely though, as a cat, that she has a grasp on the concepts of "composing" or "music". So, what she hears is certainly heard without the imposition of those concepts.