dropShadow Pixel shift

programming flash
1

I’m adding a drop shadow on a vector based movieClip and am placing it on the stage w/ a x and y tween…it is in the library and am calling to it via its class name.

It is placed on the stage just find and looks good, then once it is rolled over it has a 1 pixel shift…after that it never does it again…

Would anyone know why I am getting the pixel shift on the first time it is rolled over?

basically it looks like so:

addChild(introBtn);

introBtn.twn3 = new Tween(introBtn, "x", Strong.easeOut, brainOB._pageWidth / 2, (brainOB._pageWidth / 2) - (introBtn.width / 2), 1, true);
introBtn.twn4 = new Tween(introBtn, "y", Strong.easeOut, 1500, (brainOB._pageHeight / 2) + (startCapTxt.height), 1, true);

_dropShdwFilter(introBtn);

function _dropShdwFilter(obj:Object):void {
var shadow:DropShadowFilter = new DropShadowFilter();
shadow.distance = 3;
shadow.angle = 45;
shadow.alpha = .55;
shadow.blurX = 8;
shadow.blurY = 8;
obj.filters = [shadow];
}