I've had my iPad since launch day, and have been very pleased with its performance. One small thing, though, has been bothering me, and I'm wondering if it is normal. The black front right-side edge of my iPad (when held in portrait mode, with the home button at the bottom) becomes quite warm even hot* to the touch. The warmth becomes noticeable after about 5 minutes of use. The left, top and bottom black edges, meanwhile, remain cool to the touch. Do I have a defective unit, or is this normal?