Magnitude is determined different ways. It is 5.2 as Moment Magnitude (Mw). Moment can be determined as Ms or ML....it has to do with how it is measured. For earthquakes less than M6, it may be not so common to get the Magnitude as Mw.......but, we need a seismologist to explain whether it is how it was measured, or if it was just downgraded in general....
Chris