It's not really useful. Generally speaking, Hermione is going to be a strong enough fake claim to warrant a bit of a pass anyway. The bigger problem though, is that if you're town, by outing that you know Hermione is in the game, you can really only be one of a small handful of roles, and all are pretty important/major. Hermione is a loner, with very few friends, so there aren't many characters with a decently strong connection to her. You would have been better off saying nothing.
@Michelle Why do you town read me?