Check Light Indicator ON

Have the codes read. You can buy your own code reader.
Some large chain auto parts stores will provide this service free of charge. They will also clear the code with the tool.

It might be something other than an EVAP code that just set around the time you were fueling. See if it returns.

Post back with the codes. :)

How long ago was the rain? The check engine light should be polled to get the codes. Are you saying that when you now start the engine and it is cold that the engine surges for awhile until the engine is warm?

DTC P0171: Fuel System Too Lean

NOTE: If some of the DTCs listed below are stored at the same time as DTC P0171 and/or P0172, troubleshoot those DTCs first, then recheck for P0171 and/or P0172.

Check the fuel pressure. Is fuel pressure OK? YES-Go to step 2. NO-Check these items: If the pressure is too high. Check the fuel pressure regulator, and the fuel return pipe. If the pressure is too low. Check the fuel pump, the fuel feed pipe, the fuel filter, and the fuel pressure regulator.
Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.
Check the Primary HO2S (Sensor 1) output with the scan tool. Does it stay at less than 0.3 V or more than 0.6 V? YES-Replace the Primary HO2S (Sensor 1). NO-Go to step 4.
With a vacuum pump, apply vacuum to the EVAP purge control solenoid valve from the intake manifold side. Does it hold vacuum? YES-Check the valve clearances and adjust if necessary. If the valve clearances are OK, replace the fuel injectors. NO-Replace the EVAP purge control solenoid valve.