In September 2005, when the price of gasoline was spiking after Hurricane Katrina, a reporter of ours asked the Stewart's convenience store chain why gas prices at Stewart's were rising faster than elsewhere.

The Stewart's president explained that, rather the stockpile gasoline, like bigger retailers do, his chain buys gas on what's called the "spot market," meaning they purchase fuel on an as-needed basis and are more susceptible to sudden price fluctuations.

I'd like someone to explain to me, then, why the price of gas at the Stewart's closest to my house rose by 8 cents between Thursday night and Friday morning when the national wholesale price of gasoline fell by 7 cents on Thursday.