Gas Prices

I've noticed an interesting phenomenon in the last week. Last Monday, I stopped on my way home from physical therapy and got gas at $3.86/gallon. On Wednesday, the SAME gas station was charging $3.99/gallon and on Friday it was up to $4.15/gallon. 28 cents increase in 5 days sure seemed like a lot to me, but that paled to what we saw yesterday.
At 4:45 PM, we saw a Shell station selling unleaded at $4.15/gallon.... Not even 4 HOURS later the same station was selling the same unleaded gasoline at $4.35/gallon. How on Earth do prices go up 20 cents in 4 hours?
I don't believe for one minute that the increases are from cost increases. I think that gas stations are speculating on the effects of Hurricane Ike and the impact the storm has had on the Houston refineries and based on that speculation, these stations are GOUGING consumers. These operators should be ashamed of themselves for taking profits in the face of a natural disaster and from their neighbors, many of whom are already struggling.