Every computer controled Corvette I have had (90 conv, 94 coupe, and the 01 I have now) have done this. And my Crossfire does the same thing. It's normal. These cars are always under the computer's watchful eye, so something will always pull power away. Even when parked in my garage, I have to keep a charger on my Vette or the batt. will die in about 2 weeks (seldom driven/garage queen)... These systems monitor so many emissions, saftey, and about 700 other features, that there is bound to be a "power surge". If I press my brakes, with the headlights on in my vette the heads up display will sometimes dim for a nanosecond. It's just part of the ghost in the machine...
Regards,
Jason