I think it feels "inappropriate" because this isn't like a "new friend" or "coworker" or "teacher" or "church member" or whatever. This is someone who I don't need to know things about for her to do her job. Granted, she's pretty open/honest with me - but its not things I ask, usually, it's mostly things she brings up that relates to the conversation.

I know I could ask her the things I want to ask her (specifically I really want to know her favorite book, if she drinks coffee and when her birthday is (month/day only - I adamantly do not want to know how old she is lol) ) I have no idea why I want to know these things, and I don't see how I can benefit from the knowledge of it so it kind of feels "stalkerish".