Patrick De Haan, a petroleum analyst at GasBuddy, wrote on X that the national average price of gasoline has finally slipped below the politically sensitive $4-a-gallon level for the first time in many months. Per De Haan: The nation's average price of gasoline has fallen 9.3 cents over the last week and stands at $3.99 per gallon, according to GasBuddy data compiled from more than 12 million individual price reports covering over 150,000 gas stations across the country. The national average is down 52.4 cents from a month ago and…