Kudos to the team at Twitter for taking steps to protect potentially compromised users despite the fact that they (Twitter) believe they have not been compromised.  Once again, this is a great opportunity to enable multi-factor authentication to protect your social media accounts.

https://nakedsecurity.sophos.com/2016/06/10/twitter-locks-out-users-after-nearly-33-million-logins-put-up-for-sale/