I've been using GitHub pages for a while now and I always wondered why they had the "your site may not be available for another 30 minutes" message on creating

I've been using GitHub pages for a while now and I always wondered why they had the "your site may not be available for another 30 minutes" message on creating a new GitHub pages site while pushes to an already-existing gh-pages branch were displayed instantly. Neat to see that explained here.