Headlight Bounce

My 04 GT2 has had this condition every since I purchased it. I just found out that GM put out a kit to correct it. Has anyone had this kit installed and is it covered under the warranty?

www.gpona.com

everybody over there has done it

Did everybody get it done under warranty? if not you have any idea what it's going to cost me or is this something I should have to pay for as it clearly a design flaw that GM acknowledges by issuing a TSB to correct it.