My first reaction to this was what a strange thing for her to say! Invasion of personal space is one of those trendy pseudo psychological phrases which people use almost so it makes them sound superior. Before any such invasion can be construed, the boundaries of that personal space need to be defined. If she meant you were standing or leaning too close for her comfort then she should say so clearly and distinctly.
If the effects you were showing were small scale thus needing to be offered close so she could see them then she ought to have appreciated why this was done and let you know if it wasn't acceptable for her.
Was it a case of being over enthusiastic on your part? You know, the trick is going well and you're enjoying it but just didn't realise that she wasn't sharing it as well as you thought?
I'm reluctant to ask this but I'm sure you'll appreciate my being frank (no name jokes please!) was it a question of personal hygiene? Had you been eating garlic or forgotten the Right Guard or something?
Was it that she wasn't really interested in the magic and thus missed the point of close up?
Again, I'm reluctant to ask this but - was she wearing a low cut top or something which might have made her feel uncomfortable about with your being so close?
I can appreciate that this is a right bummer as the next time you do anything you'll be worried about getting too close and may come over as being too distant - you can't win at times. Unless you take up stage magic!
It's an interesting and important point to have raised - when is Close Up magic too close up?
