I'm running a McBook Pro, Mountain Lion, using the most current stable release of Chrome (Version 23.0.1271.64). I also use this extension on another computer which is a Windows 7 PC also running the most current Chrome. I use the extension entirely offline, no sync.
On my Mac, the extension always seems to save the master password in the extension drop down menu, despite having the setting set to "Never store". This is true regardless of whether I set the "General" options to keep the master password hash. On my Windows 7 PC, I don't have this problem and the extension flushes the password box and prompts me to enter the master passord every time, which keeps my actual site passwords secure in the event someone gains access to my machine (or I leave it unlocked by accident).
My obvious concern is that the extension becomes quite insecure if I let someone else use my computer (could happen) as they can simply go to any website I use and quickly reveal my password without doing anything more than clicking on the extension. My computer is always password protected, but notwithstanding, this issue is a bit like having a super secure lock that always has the key left in it.
Let me know if I can do anything to help reproduce or debug--unfortunately I have only very rudimentary programming experience and even less knowledge of the inner workings of Chrome extensions.