I've noticed on my iPhone 4 that when I plug it to charge for the night, when I wake up it shows 100% but as soon as I unplug it, it jumps to 98 or 99%. When I plug it back it shows 100% again. Reboot returns charge level back to 100% even if not pluged. I also noticed that when I plug my iPhone not to computer but into socket, phone shows "charge complete" with plug icon and after some time it switches to charging icon with this small "bolt" on it. It doesn't do it always (today didn't, yesterday did) but just noticed it while observing this other issue. What do you think is it soft bug or do I have defected battery? Do I neet to get my phone for replacement? Thanks in advance for answers.