Alternator light came on

[black98snake]

I was at a dead stop in th 02gt and decided to play since there was no traffic around. Raised the rpm's dropped the clutch and floored the car. Alt. light comes on and stays on through 1st, 2nd, and 3rd. Keep in mind I watched it stay on as I shifted and cared less. Car under warranty. After letting of the gas in third the light goes off. Any ideas why it would come on in the first place. Brand new Alt. replaced last month by Ford.