The average price of a gallon of regular increased an uncommonly steep amount in the past week in the Philadelphia market: 20.2 cents, according to GasBuddy. On Monday morning it was up to $3.76 per gallon, 27.2 cents per gallon higher than a month ago and 2.1 cents per gallon higher than a year ago. And, the run of the Philadelphia market being below the national average came to an end. The national average price increased only 4.3 cents per ga…