Norton detected a Threat Rated 1 out of 5 stars

After the most recent update, Norton detected a threat from this extension. I will not be using this anymore.

This review is for a previous version of the add-on (0.3.0). 

This is definitely a false alarm

The add-on's complete source code is out there and you can see for yourself whether there is anything malicious.

You should report this to Norton instead of complaining it here.

FYI: here's the result from virscan.org.
http://r.virscan.org/report/ca10e3e138fd0552929db6c54f48440e.html