Each littel roll input implies a pitch down of the plane nose.. why?

[Nedum]

Why is there so extreme pitch down of the plane nose each time I roll the plane? No other plane has this behavior (the axes are all correct configured) in such an extreme way and because of that that the Mirage is a FBW plane it shouldn't behave like this.

If I would roll 180° I could understand that but a little degree of roll is enough to let the nose fall down.

Is that so in RL and if so, why?

 

Edit: DCS 1.5.3