Object flickers on mouse over & out?

btn0.addEventListener(MouseEvent.MOUSE_OVER, moveHoverOver);
btn0.addEventListener(MouseEvent.MOUSE_OUT, moveHoverOut);

private function moveHoverOver(event:MouseEvent):void
{
			
    trace("MOUSE IS OVER");
	this.buttonMode = true;
	btnHover.x = event.currentTarget.x;
	btnHover.y = event.currentTarget.y;
			
}
		
private function moveHoverOut(event:MouseEvent):void
{
			
    trace("MOUSE IS OUT");
	btnHover.x = -500;
	btnHover.y = -500;
			
}

It traces both MOUSE IS OVER & MOUSE IS OUT (constantly, btw) when you roll over or roll out. What gives?

All Im trying to do is bring a little box (btnHover) over each button when they roll over and take it off when they roll out. If I change event.currentTarget.x; to a number, the flickering stops.