That's one possible explanation, though I've been on usgs.gov a lot from the first I heard of this, and I've only ever seen 4.8 on it. Odd, also that the OP sharing this shared a link to 4.8 but put 4.7 in the title. But the text on that page might trick your eye, between "M 4.8 - 7 km N" and "Magnitude 4.8 mwr Depth 4.7 km".
Those of us in California are used to this. We feel the shake and look it up, and see one number. News articles get written with one of those numbers. After a while it changes, possibly a few times, to some number close to the initial report.
