If you are a G4G user, you received an email a few weeks ago about the removal of any non HTTPS callback URLs to BVSTools.com.
This is because in order G4G to be validated by Google they do not allow non SSL communications. Because of this, all call backs now go directly to the HTTPS version of the BVSTools.com website.
The HTTP (non SSL) callback has been removed from the Google API setup so any requests using the HTTP callback will now fail.
If you did not update G4G to the latest version you will be required to do so before doing any OAuth 2.0 Authentication with any G4G addon.