Just out of curiosity, are you in the left lane, even at midnight with very little traffic? I can understand someone riding people's tail when people fail to yield to faster traffic. Its one of the most frustrating things out there. I wish the US enforced this rule like they do in Germany. If you're not passing someone, then get over. Its plain and simple, and it saves lives and prevents road rage. Passing on the right is dangerous.
Not accusing you, but everyone should be more courteous and move over when they're done passing.
Sometime yes, sometimes no. There's no real consistency to it. Bottom line is most California drivers are idiots on the road, be it busy traffic or no traffic.