Sony has started issuing emails to certain PlayStation Network members warning them that their PSN password "is no longer valid" and needs to be changed.
According to the email, "Sony Entertainment Network team routinely monitors for any irregular activity, and if such activity is detected, we may sometimes reset passwords of affected accounts to protect consumers and their account information.""
Of course, there's a nasty precedent for intrusion of PSN, back in April 2011 when PSN was shut down for a week as Sony had to deal with account hacking and for some, compromised credit card security.
Sony has not offered any additional information. Stay tuned.