I purchased a 13'' Unibody Aluminum Macbook in April of 2009. I have had the computer for a little over a year now and absolutely love it. For a while, the battery lasted 3:30-4 hours on a full charge on average (mostly web browing, not heavy usage). Recently it is only lasting for 1:50-2 hours when asked to perform the same workload. It never predicts more than 2, maybe 2:30 hours of life even after a full charge. Is there something wrong with my battery, or is this just the result of an aging battery showing some use?