Auto Joined a lobby into a black screen

Was in a Aram lobby, someone had left and it took me to the 'home page' of the client, so I got annoyed and was going to see if any friends wanted to duo, as well as clearing out the notification that someone had just left. Open my friends tab and I randomly hear the "ting" sound when you join a lobby. It auto joined the 'lobby' without me clicking accept. There was a black screen, I could see my friends list by opening and closing it so I did what anyone would do. Close my client. I closed it and now have to wait 15 minutes to join another lobby because I left a lobby that was never there. Not sure how you can duplicate this, I'm sure I'm not the only person who experienced this. This is the 3rd or 4th time in many years that something like this has happened. Sorry to anyone I just dipped from =\