As an old crone type, I would say do not be shy - let a person know if you wrote a story, or a scene with them in mind. Share that with them, too. It is too easy to miss a story posting or have your RL disrupt blogging time. I say tell them, tell them now. I know I would be intrigued, flattered and curious beyond the norm if an author would tell me and it would surely kill me on some different plane if I let a writer down and never knew. Share it with them. I think it is important to both of you.