I am so glad this thread came up, I loaded all 750+ books yesterday from calibre after the battery was fully charged and played around with my new Kindle a little before bed. After seeing this thread, I went to check the battery level, sure enough - only about 25%. I charged it again, unplugged it and the continued drain makes it look like it isn't quite done yet. No problems though!
I have read about this before and should have remembered, but forgot just like I do so many things that I am not using at the moment...