People Joining/Leaving Still Heard From End Game Lobby [Client]

This is a little annoying that whenever I leave an end game lobby (the lobby with the miscellaneous stats done by each team and player, along with the chat, results, IP/EXP/MP gain, and option to report and/or honor a player), I hear people entering the lobby and leaving. I tried leaving quickly and slowly (waiting up to 2 minutes with people still inside the lobby) and I still hear them.

This always happens to me after each and any game mode, Blind, Ranked, Team Builder, Co-op vs. AI, etc.

Is it just me and my client, or is this a common bug among you summoners?