If you were indeed filling up the tank into the filler neck that can lead to fuel running into the charcoal cannister and rendering it useless. You might pull the vent lines off the cannister and let it sit for a while to allow the gas to evaporate. Or remove it and blow it out with some low pressure air. When the fuel gets in the cannister it can dissolve the charcoal and sometimes render it useless or allow some of the charcoal to get sucked back into the vent valve causing it to stick open or closed. Usually when you open the hood you can smell the fuel if it has entered the cannister. If there is no fuel smell I would suspect the vent valve.
