Not sure exactly, but I have definitely noticed while working on this course that I had to refresh JSBin from time to time, so I wouldn’t stress as long as it started working once you refreshed the page and there was not an error message. I found the same thing. That said, I still preferred using JSBin to start off with. Once you get into the code editor in later videos it should cease to be an issue 🙂
PS – Thanks so much!!! Welcome!!! Whoohoo!!!