[TechniSol]

Maybe run it down and charge it back up a couple times and see what happens? If I remember correctly I've seen one reading while plugged in and a lower percentage after unplugging on an incomplete charge a few times -usually just a couple points difference. Probably because they're just monitoring voltage while charging and at anything less than a full charge the voltage drops to the battery voltage when the charging cable is unplugged. You have to realize that in order for the battery to charge the source must have a higher potential, so the reading is higher when connected unless the battery has finished charging and the charging circuit has disconnected the charging source, or is pulsing it or some such depending on the design, battery chemistry, etc.

As for the stuck at a certain reading, I suppose depending on the state the device is in it may not be updating the percentage. If it continues to be a problem try a reset. Unless the device becomes physically hot it's probably charging just fine, merely not updating the display for some reason. Could be a firmware bug that I don't recall.