An unexpected side-effect of the facade VI, Properties, Window Appearance, Customize..., Window has title bar is that with it comes a 3-pixel wide border when you place a new instance of the xctl on a VI. If you have the border and never want it, don't just paint it transparent each time but fix the VI by unchecking this setting. If you do want the option of a border, check it; the title bar does not actually appear.
