Gas Price Drop Ends; No Spike Expected LOS ANGELES - Gas prices nudged upward about half a penny in the last two weeks after dropping more than 20 cents since May 21, but another price spike is not expected due to a decline in crude oil prices, an industry analyst said Sunday.    The combined national average for all grades of gasoline was \$1.91, said Trilby Lundberg, who publishes the semimonthly Lundberg Survey...