Gas prices are up a little on average heading into the Fourth of July weekend. Triple-A Arizona says the average price of gas is up a cent from last week to $3.12 a gallon. Spokesman Sergio Avila says the increase in gas prices is simple. “we’ve been seeing a lot of demand (for gas)” says Avila. He adds, “another thing we’ve been paying attention to is the cost of crude oil which has been increasing as well in the last few weeks.” In Flagstaff, gas is up just over a cent to $3.40 a gallon. Some stations are selling gas for $3.29 and lower. In Prescott, the average price of gas is up nearly a cent to $3.13 a gallon. Some stations are selling gas for $2.99 and lower.