With these types of earthquakes that are occurring before the main one I think that it is necessary to step back and picture what is probably taking place in the fault zone.

The rock layers are likely so highly strained over a fairly large area that some sections of the fault zone might fracture even before the main earthquake if that is possible. And I would imagine that those low magnitude earthquakes occurred because of that. And in that regard they could have been a type of precursor.

I would also expect that this process is probably highly dependent on the fault zone environment. For example, it would probably be different for earthquakes where the tectonic plates are pressing against one another with the result that one plate slides beneath the other, versus fault zones where the tectonic plates are trying to slide parallel to one another.

In any case, this is probably a matter for the geophysics experts to decide.