www.LastPass.com is overwhelmed with traffic right now, won't allow you to change your password.
They act out of utmost paranoid security concern, breach has not been verified 100%, but is likely.
Once you can, change your password.
LastPass forcing members to change passwords | Security - CNET News
another take on the situation from http://blog.duosecurity.com/2011/05/breaking-down-the-probable-lastpass-breach/:
similar website allowing automatic logins and storing your passwords in the cloud is www.RoboForm.com
Passwords are always stored scrambed, but the problem is a master password, of which a breach will allow access.