Welcome to the world of being a cat
slave owner!
That's what they do, Robbo... drive you nuts trying to figure out how you've upset them when you've done nothing wrong. A cat wouldn't be a cat unless it punished you for something at least once a day. The staring you out is a classic punishment... I expect you're sitting in the seat she fancies sitting in.
All perfectly normal and in time you'll get used to it.