CEO Behavior

I recently did a contract job helping with a dinner event at the company I used to work for. The company has a CEO I had never met before. After the event, the CEO called me into her office. I thought she was going to basically do a "debriefing" about the event. However, she didn't discuss the event at all but, instead, just asked me questions about the date I brought to the event. For example, she asked if he was my brother (I have no idea why she would think this). I feel so uncomfortable that she would ask me such personal questions. I'm curious to know what you think of her behavior and why she would want this personal information from me. It really made me uncomfortable, and I thought it was invasive and very strange. (I am female, BTW.) What do you think about it?

Sounds like she wants a piece of your date

She's married, by the way ... but maybe that doesn't make any difference.