Rolling when using the rudder is called roll-coupling. It happens - some planes do it worse than others-some barely do it. You have to correct with a little opposite aileron to the rudder motion to level the wings out and hold it steady. So left rudder - right aileron as an example.
In previous flights, I did notice that I could offset the roll w/opposite aileron, that's why I programmed in the wing mix Rudder as the master channel w/Aileron as the slave. Even at a 100% trim, I still get rolling when a hit the rudder. I wonder if I'm doing something wrong with the wing mixing on my radio.