Actually the dualshock 3 does the same thing. Awhile ago I was messing around on my PS3 wondering what would happen if I were to hold the PS button for a long time. So I did to find out the controller turns off after about 10-15 seconds. When I figured this out I may or may not have been bored lol.

Anyways that's awesome to know Alt I've never thought about that. Good job nonetheless!