Is that with the charger or over USB? If it's over USB, then from my experience that's pretty normal. You can just unplug the USB cable and put it back to get up to 100%. If it's with the charger, then see WizardStan's post. Also, if you let it continue to charge after 100%, then it will turn off charging and gradually drain to around 87% before it begins to charge again. That's normal to keep it from overcharging.