Another thought, most airplanes DO have a tendancy to pitch the nose up or down (in relation to the plane, not the ground in knife edge) with large rudder inputs.Again, this is affected by the placement and relationship to the rudder and horizontal stab/elevator and is likely due to some aerodynamic flow changes over the stab when the rudder is deflected.
Most all RC airplanes I have flown will also display this. Most seem to slightly pitch the nose down (one would do so violently, even in level flight, not a good thing close to ground!).
In fullscale you would likely have to be paying real close attention to notice whether you have some elevator pressure in to counteract it.
Dave Hamblin
(formerly DaveH on old site!)