I put my 3 day old MBP to sleep last night with a 90% battery level (with the A/C adapter unplugged). I had calibrated the battery the day before. This morning, when I opened the lid, nothing happened. I thought this was odd. I then pressed the power button and heard about 1 second of the startup tone and then nothing. I repeated this twice more with the same result. I then plugged in the A/C adapter and the MBP booted up. The battery level was 86%. What do you think has caused this? Do I have a defective battery or something more serious?