Anyone have the black Griffin Power Jolt Car Charger for the iPhone 3G? Anyone have any bad luck with this charger? I had my phone plugged in and the phone filled up according to the charger, and then it kind of went back down a bit and the charger light went from red, to green (indicating full) and then back to red. I feel like ever since then, my iPhone 3G batter has not held a charge as long. Am I just being paranoid?