Thank you all very much for your replies. It is helpful.

It is not my imagination that I am being watched. I have had three different managers ask how I am...drives me nuts! However I was in a meeting with two managers and several colleagues and this particular annoying woman manged to upset another person right in front of us. She has a really unfortunate manner and seems to get right up everyones noses. My manager caught my eye so I know she noticed.

It is awful how one person can cause such bad feeling isn't it.