My last battery popped, and on Monday, Apple store gave me a new one. The lady told me that it was best not to keep the power connected all the time. So I charged it to 100% and pulled the plug. It runs down incredibly fast. This morning it's been unplugged for almost an hour, doing just a bunch of web searches, and it's already down to 37%. This isn't normal, is it? I was able to watch a 2 hour movie on a full charge for my old battery. Does the charge get better over time?