What could cause the camera to turn on automatically while the phone is in standby? I have a Samsung Galaxy S5 (the blue one just to help set the scene) running Android version 4.4.2

My phone was sleeping beside me peacefully on my desk in standby mode (or whatever you call it when it's just a blank screen not being used).

Suddenly, the screen lights up and to my surprise the camera is active - with no human intervention whatsoever. There were also no notifications of any kind at this point that might have had a hand in it.

What could be the possible causes for this to happen? Are there any conditions is which this might be expected? Is it a bug? Or maybe worse, could it be a malicious application trying to "catch me in the act"?

Additional information that might be useful:


When the camera started it was the main camera that was active, rather than the front camera
Looking through the phone and camera settings, there is nothing enabled (or even available) that might explain this happening. For example, there is no quick start camera gesture or voice command
Not exactly a solution, but this seems to be part of the problem:


  Launch Camera directly from lock screen
  
  Time is often of the essence when trying to capture the perfect
  picture. The Galaxy S5 lets you bypass the lock screen to snap a
  picture. Simply swipe the camera icon up (in the lower right hand
  corner) and you’ll launch directly into the camera app! If this
  feature isn’t turned on you can do so by:
  
  Go to Settings > Lock Screen Check “Camera Shortcut” You’re done! Even
  if you have a pattern or password lock set up this will let you take
  pictures without unlocking your phone.


How this is being enabled is anyones guess.