Nope, the northward movement was apparently real
Posted by Lowell on July 06, 2001 at 08:50:23:

If you surmised that the appearance of a northward motion to the earthquake
sequence at Tres Pinos was real, you have some additional confirmation
from the Watsonville Ml 2.8 and the Rohnert Park M3.7 this morning.
See California earthquake link above for details.