It's a 403 error, so it's probably unlikely it has anything to do with browser cache (but of course possible, though I don't know what Django would need from cookies/webstorage/cache). I did try on another machine in a incognito window and got the same thing 3 times.
OK, really sorry about that. We're working on it back here, we can definitely see a caching issue somewhere in the pipeline. Would you try once more in incognito mode?