Invalid token

I think I just stumbled into a bug with the minecraft launcher, sometimes when I load the launcher
and click the butten beside the character name on the login screen, when its trying to login a message
popped up sayiing "Invalid token" then I had to relogin.This is very annoying can someone tell me whats going on! I dont want to keep on logging in with my username and password all the time since there is an option to
login without doing that.

ps- since the launcher is nice to me I cant seem to replicate this error but it happened to me before alot of times, so I cannot give you a picture till it randomly happens