There is nothing particularly odd about this swarm.
There is a difference between an aftershock sequence and a swarm of earthquakes - both
in causes of the events and in the number and frequency over time.
An aftershock sequence is generally due to readjustment of strain after a
strong mainshock. The earthquake often tend to avoid the area where the
mainshock occurred (that is, they do not occur on the rupture plane), but occur
in the region around the mainshock where strain conditions have been changed.
The frequency of aftershocks follows the Omori Law which states that there is an
exponential decline in events with time after the mainshock. There may be
more than one mainshock in which case several Omori sequences can be
occurring simultaneously. The mainshock is generally due to rupture along a
fault and physical conditions are described by elastic rebound theory.

On the other hand, swarms are a whole different ballgame. There are two
hypothesized causes for swarms of earthquakes. 1) Magmatic or plutonic
activity and 2) generation of a new fault/fault zone. The Coso swarm is probably
related to the first of these, although some have argued that new strain conditions
in California are beginning to create a San-Andreas-like fault from Southern
California up through the Long Valley area, passing through the Coso Junction
region. Dr. Susan Hough of the USGS in Pasadena has studied this area extensively
and an e-mail to her there might get a good response (although she might be
very busy at this time with this swarm). Swarms come and go, there generally
is no mainshock and earthquake in swarms are usually less than Ml 5.0. The
Omori law does not apply to swarms because they are not caused by strain
release and readjustment. Since most earthquakes in California in the past 20
years have occurred in the California-Nevada border region, they are generally
related to earthquake swarms, not to ruptures along long fault lines. So, it would
seem that most earthquakes in California at this time are swarm-related.
Swarms can last from a few hours to several weeks, but seldom longer.