I've had my unibody 2.0 since November. It's always said 5 hours or so when i open it up fully charged. This week it's started fluctuating wildy. While typing this post it's gone from 3 hours 23 mins to 4 hours and five mins....it started at 2 hours....now it's up to 4...very odd. Any ideas on why this has started happening all of the sudden?