That's odd. Not sure where linkedin asks for passwords, I thought they used OAuth.
FWIW they also try and get Oauth/permissions when you sign up. You can verify the account the usual way, clicking on an email link, or use OAuth (of which it'll dutifully want permission to see your contacts). LinkedIn pushes the latter.
I don't see where they take passwords...
"LinkedIn used its member's identities without consent and broke into their third party e-mail accounts to send promotional e-mails to the members' contact lists"
Does sound worrying, I hope they're misunderstood.