Cali has their own special fuel requirements, so they get special pricing. Required by a special law. Other places also have special fuel laws.
Obviously, the mean evil big oil companies just arbitrarily reduced the prices of fuel, in a similar way as when they just arbitrarily increased the prices of fuel. Laws of supply & demand, refinery capacities, other industries increase/decrease in energy requirements, limited special fuel blends demanded by special places, & increase/decrease in fuel demand by the traveling public have no effect on price ups or downs. The oil companies only do this to take advantage of the publc, no matter what the price is. That is the only possible reason for gas to be more expensive in special places & less expensive in others. Why do the big mean oil companies do this, without any reason as to supply or demand? Because they are big & evil.
Or it could be a predictable pattern of up/down prices following certain supply/demand parameters. Nah, that's just crazy talk.