The notice is set up to be displayed only once, when the extension gets updated to version 3.0.2. If you see it more than once (in a single browser), there might be a bug in the browser itself. If you can, please send me more info about it. You can also try to uninstall the extension (I guess you've already done that part hihi) and install it again after the browser restart. That may help.
Also, if you have some kind of sandboxing software like Sandboxie, it can cause this kind of problem with addons, you should see the instructions provided by sandboxing software developers.