Jeff Matthews: Is This The Sign of a Top?WSJ: Big Oil Firms Curb Pump Prices, Put Squeeze on Competitors. [$]Quotes:Major oil companies and refiners, under attack for their soaring profits, are restraining prices at the pump.The result: Gasoline can be cheaper at branded gas stations operated by companies such as Exxon Mobil Corp. or Valero Energy Corp., the nation's largest refiner, than it is at