Just how serious is this? Is this just some guy who stumbled on a hack and can't repeat it? Or is this some fundamental flaw in Paypals security. In other word

Just how serious is this? Is this just some guy who stumbled on a hack and can't repeat it? Or is this some fundamental flaw in Paypals security. In other words, do I need to worry about my Paypal account? My account is link to a checking account and cc.