enderman moving very fast when it have been stared at.

when i have stared at a enderman, it will move faster then normal. when if you provoke a enderman by attacking it, it moves the normal speed.

HOW TO REPRODUCE:

1. spawn a enderman
2. look at it in the eye
3. look how fast it moves
4. spawn a second enderman
5. attack it
6. compare the enderman you attacked to the one you looked at in the eye.
as you can tell the speeds are very different.

is this supposed to be a added feature or a bug?