It's probably overkill to save the preference. A good-and-still-simple solution would be to include a (non-linked) replica image of the original button along with an explanatory link to github.com.
Bravo. This is so simple, I can't believe I didn't think of it -- just put a "github homepage" link/image on that pop-up that users can then right-click to their hearts content.
And here I was thinking about adding cookies and saving client-state. :)
