Looks like there were some errors at 9:47am UTC, only a small blip though https://status.github.com/messages
September 11, 2018
14:48 Central European Summer TimeWe are investigating a small portion of our users unable to access the site.
13:20 Central European Summer TimeWe are investigating reports of elevated error rates.
12:09 Central European Summer TimeEverything operating normally.
11:47 Central European Summer TimeWe are investigating reports of elevated error rates.We are investigating a small portion of our users unable to access the site.