This is the same thing as everyone going to a bank that has a minor problem and withdrawing all of their money. They will kill the bank, and most will end up losing their money, even though everything would have been fine, the bank would have survived and their money would still exist, if they didn't panic and withdrawal.
The pipelines and delivery trucks are all set up to provide us what we usually use. No more, no less. Buying more than normal over stresses the current logistical system, and will cause shortages, even if your stations and trucks are provided fuel by refineries and pipelines that are still running at 100% capacity. Areas that are unaffected by the refinery and pipeline problems in the South are causing their own price hikes and shortages because of changing their buying patterns.
This stupididty will cause outrageous prices in order balance supply and demand. Of course then demand will take a steep decline once the prices rise too much, and comsumers already have an abundance of fuel in their vehicles and storage. So, we will end up with prices dropping below pre-Katrina values to compensate again. Eventually the prices will raise again to pre-Katrina levels, and continue as they were originally, and there will be no shortages in areas not directly affected by the storm.
But, this scenario only works in a free market. Government price caps will screw the equation, and we will be stuck with limited supply because stations and oil companies won't be willing to take a possible loss on fuel sales, so we will never reach the "gas is too expensive and I already have enough gas from panic buying" portion.