It happened again because your IP changed, probably..
Btw, don't keep rejoining server once you get kicked from server for false ban/VPN, server will think you are spamming the server with kick message thus it will block you from connecting to server for about 15 mins to stop the spam. You should restart your internet then join again and if it does not work, ask admin for help..
Btw, PM me your IP if it happens again..