Well first we have to remember that none of us can read people's minds. Especially when all I know about this girl is from what you wrote.

But if I went to get a chair, I might want to make eye contact with the person sitting there and ask if it was ok if I took the chair. If you were staring at your phone and not looking up, I might have felt like you didn't want to talk to me. That's the way I feel when people don't make eye contact.