Hey John!
My assumption is as follows:
When you initially slap her ass, she's still under the assumption you're a powerful Magi who's currently keeping her in the house against her will, therefore she's being incredibly submissive.
When she realizes she's not in any immediate danger and that you are also stuck there with her, she changes her approach, which is why we see her tone change.
Good spot all the same! Interesting to see how things pan out going forward!