Is everything snapped to a grid? Looks like your circle is not centered on the grid or the radius is not a multiple of the grid.
We (librarians) start with everything based on the grid units (0.1 inch) that our designers are expected to use. Anything that they need to position needs to work with their points on the grid.
Within a symbol, we use some smaller grids to position things properly. Using your item as an example: if we wanted it to be 0.5 inch circle, we would put the center of the circle and the center of the number on a 0.05 inch grid so that the ends of the 0.25" radius (that they will place a line up to) will be on the 0.1" grid.
There have been a few things where matching points up inside of a component has needed down to a 0.001 grid but the designer is never expected to place anything to those points.
