The average retail cost of a gallon of gas in Maine has dropped nearly 3 cents in the past week to an average of $3.50. Price-monitoring website MaineGasPrices.com reports Monday that the in-state price is now just a penny above the national average. Prices in Maine are now almost 40 cents lower than on the same day last year and more than 21 cents per gallon lower than a month ago. The Maine prices are based on a survey of more than 1,200 gas stations in the state. A company analyst is warning consumers not to get too comfortable with the prices, as they are expected to start rising again soon.