Hey all. The i50 in the URL is a post-GTM DNS name that SHOULDN'T appear and will cause the cert error. Our platform team is investigating why this pops up from time to time and we should have it fixed sooner than later.
Part of DevCentral and F5.com's charter is to "eat our own dogfood" so sometimes when we're testing new features and infrastructure configurations, we break stuff. Hopefully we can get this fixed soon. It shouldn't happen that often but if you're running into the error constantly, a browser cache clear does seem to help (yea, I know.... turn it on/off.... my old IT days coming back)