Has anybody ever noticed this before?

I've known for a while now that the experience range is about 2/3 the distance from your character to the edge of your minimap, so I've just eyeballed it and hoped I was in range.
However, I just noticed today that you can see the range in game. Take a look here: http://i.imgur.com/iv4fa3M.jpg
If you look closely you can see that there is a circle in the center of your minimap that's a bit less opaque than the edges. This circle happens to be exactly the range required to receive experience from a monster a party member has killed. It's sorta hard to see but once you've noticed it it's pretty easy to keep an eye on.
Hope this helps you people being powerleveled out. Have a nice day :)