SWA won a lot of customers when the smartly hedged fuel before the run-up, other carriers had to raise prices, but SWA could keep fares low because of how they locked in their fuel costs, which also allowed them to offer free checked bags, etc. However, their hedging programs have not been as fortunate as of late, and they've needed to adjust their pricing just like every other carrier, and lets be honest those, "free" checked bags are not really free, they're imbedded in the fare you are paying.