Do people imagine mobile phones make them invisible?

Or is it everyone else who becomes invisible? I was trailed at close quarters by a big girl weeping copiously as she detailed at volume the very many, very intimate reasons why she was upset, I was getting drenched, deafened and thoroughly depressed and she was practically on my heels so I stepped into a doorway to allow her to pass. She did spot me then and paused her wailing long enough to give me a squint-eyed What's- the-matter-with-you? look