Don't worry about it, this basically means where the server is having it's usual restart. Or if you're having problems with your internet it will also cause problems getting into the server. The game /should/ return to normal soon trust me, are you seeing this all the time or just a few times, I mean like later on does it let you in?
Plus, if a whole bunch of other people are trying to get into the server it will cause you to lag and get you stuck on this screen for a while, hope this helped. x3
