WASHINGTON (Reuters) - U.S. motorists finally got some relief at the pump as the national retail gasoline price fell for the first time in six weeks, dipping a penny over the last week to $2.91 a gallon, the government said Monday. Motor fuel costs dropped for the first time since March 27, but the price remained up 72 cents from a year ago, based on the federal Energy Information Administration's weekly survey of service stations. EIA Administrator Guy Caruso told Reuters last week that the vast majority of the recent jump in wholesale gasoline prices had been passed on to...