It appears my MBP is leaking electricity too. I can charge it up to 100% then disconnect it and leave it sleeping overnight and when I come back to it, it's lost 1/4 of its charge. I'm wondering wether it's not actually going to sleep, it keeps getting woken up. The only way to tell what it's doing would be to open the lid, which wakes it up anyway.

It's getting on for 2 years old, so I'm probably not going to bother apple over it.