AUGUSTA, Maine (AP) – The average retail cost of a gallon of gas has gone up a penny over the past week. Price-monitoring website MaineGasPrices.com reports Monday that the price is averaging $3.46 a gallon. In-state prices remain 21 cents above the national per-gallon average of $3.25. Maine prices are 3.9 cents per gallon higher than a month ago and 10.6 cents per gallon lower than at this time last year. The price is based on a survey of more than 1,200 Maine gas stations.