Nokia's battery indicator lies to you, ASUI does not. There is nothing wrong with your battery. Nokia's hardware/software somehow determines a max value that is different for every battery. My battery is around 97%. The value ASUI displays is directly from Nokia's software, the same software that sends a signal over dbus when the battery begins charging and another when it ends charging.

Does Nokia's battery indicator have separate images for charging and full-but-plugged-in? ASUI includes a replacement for the statusbar battery that has two separate icons for those states. You can enable it in control panel. And ASUI's battery icon also replaces the bluetooth and wifi icons, and touching it opens ASUI.