That's right, sorry to be the bearer of bad news. LastPass users need to change their master passwords right now. From their blog https://blog.lastpass.com/2015/06/lastpass-security-notice.html/
LastPass Hacked, Change Your Master Password Now
From the media, with a bit more detail.Nonetheless, we are taking additional measures to ensure that your data remains secure. We are requiring that all users who are logging in from a new device or IP address first verify their account by email, unless you have multifactor authentication enabled. As an added precaution, we will also be prompting users to update their master password.
LastPass Hacked, Change Your Master Password Now