Yes cheyne stoking !

Hello,
Sorry for this mistake.
I'm french and my english is very poor
I want to tell you than i'm playing arma3, i take the helicopter. For now all be done, the flight controls response very well. When i pull the mouse, helicopter go to backward. When i push, helicopter go forward.
But... after 2 minutes of playing, the controls are when i push, heli go backward. When i pull, heli go forward.
It is'nt a bug ?