I remember turning on my iPhone and briefly seeing a picture of myself from a time when I had not taken any photos of myself. In fact I had not been using the front facing camera at all.
I think user ‘sixothree’ was stating that a picture would show after unlocking the phone, not after a call. I myself, have had it happen to me several times couple months ago and thought it was really creepy. It almost seemed as if someone was using the front camera without my knowledge. Thought it to be glitch or something at that time.
Extra creepy.