One other thing to note is that by default lastpass allows reverting to your previous password for 30(?) days. The option is in account settings -> advanced -> "Allow master password changes to be reverted".

To be safe you would probably want to disable that then change your password again. Just don't lose your new password as you then can't revert.

See https://support.logmeininc.com/lastpass/help/recover-your-lo...