I got a 5 minute join que penalty?

wtf? I just joined a game and we started selecting champs (playing pvp), on the last 10 seconds before we were about to enter I just got kicked from the champ selection and returned to the main menu I then went to queue again and as soon as I did it had appeared, it says in the photo i posted that i had left or declined an invite but I've been playing match after match and never declined anything. please explain to me what its happened =/ very confused and slightly annoyed though it is 5 minutes still frustrates me that I'm beaning penalised for nothing.