In my latest Vanilla 2.0.9 upgrade I now get a notification on the my plug-ins page that tells me if a newer version of a plug in is available...sweet! Problem is that it is reporting a new version of signatures is available (v1.2) but after trying to find the file it mentions to edit I found that it is reporting a Vanilla 1 version of "signatures". Bit confusing but I don't know if it is a plug-in problem or a Vanilla problem.
There was a bug with the addon site that lets people upload multiple plugins with the same name, and then the updater gets all confused. My Signatures plugin is a from-scratch version of what I thought Signatures should be. But there was already a plugin for V1 called Signatures, I guess, and now it is conflicting.
It happens because the extension update check does a search for the name of the extension. I think it would be a good idea for you to release a version 1.3 of this extension even if nothing has changed, because that way the dashboard won't say it needs to be upgraded.