One of two things. They made a change to one of their files that I believe caused the error. If you had the old version of the file cached on your browser, you may still have been able to use the site.
Second reason could be due to how some websites deliver content regionally to make things load faster. You in Minneapolis would connect to a server closer to Minneapolis than say someone in Miami. If RC fixed their issue and put it out to the new servers there can be a lag in how long it takes for users to see the new version of the site. While it really shouldn't take that long that person in Miami could see the updated site before you in Minnesota would because the server closest to Miami already got the update, but the one close to you didn't yet.