Lately, my Macbook Pro's battery has been losing charge more rapidly than usual. The charge lasts two hours or so of me performing basic tasks (writing, browsing and occasionally compiling code and using the Adobe suite). It used to last twice as long. So I go in to the power preferences and it tells me "service battery". I usually fix things myself, but I'm wondering why I'm getting that notification? Could something awful happen to my battery? I mean, I could buy a new one and replace it myself.. I'm just trying to figure out if there's any degree of urgency involved and why OS X is choosing to notify me of this. The Macbook Pro is a 13" unibody from mid-2009 (battery inside, with tri-wing screws). It's out-of-warranty.