It drives me mad. Whenever she comes round she picks up cards on mantelpiece and reads them. I don't mind if it has been my or DH's birthday (although I still think it I would say 'do you mind if I look at your cards?) Cards sent from friends eg. on anniversary of my mother's death. These are personal and I don't feel I should have to hide them in my own house. She also does it with any post we have lying around - on kitchen table etc.
Am I being ridiculous??