I calibrated my new MBP just like it said to do on the Apple website. http://support.apple.com/kb/ht1490 At first, my battery life was 10 hours and 32 minutes. Then in a minute, it dropped to 9 hrs and 32 minutes. Then in a couple minutes, it dropped to 7 hours and 30 minutes. Now, a few minutes later, it's back at almost 9 hours. Is this normal?