A paranoid friend

I have been studying with a friend lately. I can't help to notice that she has some distinct habits. Every time she went to the restroom, she would pack her study materials and bring two or three heavy bags with her to the restroom. And every time I passed by her when she was typing her email in library, she would cover up the monitor right away (like I was interested in what she was typing.) And today she yelled at me because I left her study materials and my bag pack unguarded for a few minutes when I went to the restroom while she was away with her purse, but I did tell her I was going to the restroom ahead of time. What the ....! We have been close friends for years, I wonder what happened to her, she wasn’t this paranoid before.