There was a bit of a break at the gas pump last week as prices came down across all 50 states. GasBuddy says average gas prices in Minnesota fell 18.5 cents a gallon in the last week, averaging $4.12. A total of 15 states saw the average price of gas drop below $4.00 a gallon. The average price nationwide fell 19.5 cents to an average of $4.26 per gallon. The national price of diesel fell 15.5 cents compared to a week ago, now at $5.43 a gallon. GasBuddy's Patrick De Haan says growing optimism around a potential U.S.-Iran agreement helped ease concerns over global oil supplies. However, uncertainty surrounding a potential deal saw oil prices edge higher Sunday night. De Haan says short-term relief could give way to another upward swing if the negotiations between the two countries break down in the coming days.