I got my ipod shuffle today (2nd gen silver clip model). It's alot smaller than I thought, so am really happy with it. However, I plugged it in via the USB dock to charge it and transfer music. I left it on to finish charging. When the light turned green, I took it off, but didn't actually use it. A few hourse later, I plugged it back in to transfer some more music. The light is now orange (and has been last few hours since I plugged it in for the 2nd time), indicating that it doesn't have a full charge yet. Is this normal? If not, should I try and get a replacement, as I don't want one with a duff battery.