Poor champ select system

So I am a regular player and do not have bans or anything against me but something happened today that really aggravated me. I was in champ select and was last pick. I took my champ and went into my runes to make some last minute edits but since I never clicked select champ it booted me from the game and gave me a 6 min penalty. If I clicked on a champ then I am clearly there but instead of doing the normal thing and just auto selecting the champ that I had clicked on it boots me from the game and gives me a penalty. I understand the idea of a lock in button but if you click a champ and forget to click that final button shouldn't the game just take the champ you selected? Am I the only idiot this has happened to?