Rated 3 out of 5 stars

All the passwords can still be seen by clicking the show passwords button in FF although Keychain is locked and it doesn't ask for the Keychain password.

edit: never mind few restarts always help.

This review is for a previous version of the add-on (1.0.1). 

I believe that firefox caches the passwords for a short amount of time (maybe a minute or so?) so it's possible that this is causing the behaviour you are seeing.