Mass. gas prices drop a penny By Ira Kantor/ BostonHerald.com Monday, November 5, 2012 Bay State gas prices are down another cent this week, days after Hurricane Sandy tore up parts of the East Coast.            According to AAA Southern New England, self-serve, regular unleaded gas is currently averaging $3.65 a gallon, 18 cents above the national average of $3.47. Prices locally are down 23 cents over the past month.            A year ago at this time, the Massachusetts average price was $3.39.            Midgrade unleaded gas is down another 4 cents this week to $3.81 a gallon, while premium unleaded dropped 3 cents to $3.95 a gallon. Diesel fell a cent to $4.08 a gallon.            The range in prices in the latest AA survey for unleaded regular is 51 cents, from a low of $3.45 to a high of $3.96. ( -— ira.kantor@bostonherald.com )