Not an expert in the 330 in any way but I would ask if the a/c is balanced? If the trapezoid is not exactly centered the wind indications on the ND can be alarming wrong....which would give wrong drift angles I presume. Next time you're flying just a apply a little rudder with the AP off and watch the ND wind vector. Even better do it inthe sim...the result should be the same.
Having said this 3-4 degrees does sound a lot. I have seen it 1-2 degrees out if the IRS is out of kilter....comparing the wind values on the ND usually shows up the difference or alternatively pull up the IRS positions and look at the drifts.
Standing by to be flamed by those with more gen!