To me it just looks like she's very comfortable with you so felt no qualms in telling you she was coming over. At least she "warned" you instead of just showing up at your door.

She may be a bit unreasonable by not accepting that you have other things to do. That's the way she sees things, though, and everyone has their own perspective. I wouldn't worry about it.

Why can't she just mingle with her parents and their friends, though? But if she's uncomfortable around them, why can't she just go to her room?