I got leave buster for no reason

I was in this late game ranked match when suddenly when i was in the enemy base the game gave me the "attempting to reconnect".So i was ok.. lets check if youtube is working.Yes it was working fine.I waited a bit for like a minute and then close and reopen lol.Then after 1 minute of loading screen i was back in the game.Sooo i was afk for like 3-4 minutes and now i recive leave buster for 5 games and a 20 minutes wait timer.. way to go riot!