RPG Auto-firing After Weapon Switch

There have been numerous instances where I will be engaged in a gunfight, and when I swap to my RPG mid gunfight (mid gunfight meaning...I'm actively auto-firing weapon) I hit 3 mid firing and simultaneously lay off LMB, RPG is pulled up, I press RMB, and it automatically fires. It is almost as if my input to fire (LMB) was queued, but because I pressed '3' to swap to the RPG before the action executed, it instead executed on the swap.

I have repeated this numerous times. Please try it for yourself. I looked at my settings to see if I had duplicate keybinds...I don't, which I shouldn't because I haven't altered the default binds. 

See link for reproduction: https://www.youtube.com/watch?v=E1YXp5u3GCQ