Megosztott hang

I found an old phone in the back of my junk drawer today. It hadn't been turned on in three years. When it finally buzzed to life, a notification popped up immediately. A message from an unknown number, dated exactly one hour after the phone had originally died three years ago. It said: 'Check the bathroom mirror. I’m still standing exactly where you left me.' I laughed. Just a glitch, right? But then I notice