Something is really wrong with Sony PlayStation as it gets hacked very often. The PSN or PlayStation Network credentials of 10 million users have been hacked and posted on the internet, by a group of hackers.
Although Sony has said that the PSN was not hacked, it is bit hard for me to believe, as have saw the user id and password hashes, with email id posted on the net.(No I am not sharing the link with you)
It is advisable to change the password of your PSN id.