It happens with many and it happened with you today ... not too much to worry about it but dont make it a habit . LOL .
yeh one of my friend got banned while he accidentally clicked and didnt care to notify google. he got banned within 24 hours! google is fast indeed and if you are not already banned for clicking own ads, expect to get banned soon.
Um... I don't think thats right they sent me an email saying that it was ok because accidents occur but just try to advoid it as much as possible. They even said if it happens again there is no need to contact them.
If "your friend" was banned for accidental clicks, I think we can pretty sure it was more than a few "accidental" clicks.
I did my accidental click, just one click, for a long time ago (8 months or more). because I scroll down the page but slow page loading and got click on the ads instead of image. I had reported google instantly and google replied "thank you for your honest". Just only one time I did it.