The Apple light isn't on, in fact, there's no light just for the apple.
The way it works, the is just a hole through the case with a plastic shield in it. When your backlight is on, it shines through.
What you're seeing is that when the LCD is off, the LCD is not blocking light. If there is another bright light on the other side of the screen, the bright light will be seen through the LCD screen. You can test this by putting your display to sleep and holding it up to a bright light or sun.
I can't take a pic right now because my phone is upstairs, but it's perfectly normal and it won't harm anything.