Yup, I'm not surprised. I've been very suspicious of Extensions in both Chrome and Firefox.
Since they are 3rd party developed, we have no idea what is it doing. The only 3rd Party extension I use is AdBlock Plus. I'm sure its doing something with my browsing history, but I don't know if its tracking my information used in Gmail or logging into other sites?
Another suspicious browser feature is Notifications. You would think notifications are for the Chrome related information, but 3rd party developers can create their own notifications. So when you go to any website and it prompts if you want notifications you are possibly enabling an unsecure feature in your browser.
If you click "yes" those notifications can be whatever the developer wants them to be. It may or may not be related to the actual website that prompted it.
So clever and frustrating at the same time. Its hard to trust 3rd party applications, but in the Linux world, everything is 3rd party.