Yeah it might have, in addition to refresh rate the position is the actual GPS/blended position from the ship's INS... if the controller knew all his dots had ADS-B lateral precision he may have been more concerned with dots trending to the merge. Secondary radar (Mode C) is fairly sloppy, primary radar precision depends on the installation, tower/approach radar is more precise that ARTCC but I don't how it compares to ADS-B/GPS.