2000 Crown Vic evap

While driving home today, i had the front windows cracked to let in some fresh air. All of a sudden there was a strong fuel smell and the check engine light went on. I pulled over and poped the hood, nothing ovbious. I went to autozone to have the check engine light scanned and they gave me the code P0442 and told me there is a small leak in the evap system. They told me that i just need to replace my gas cap. I dont think its the cap because if i could smell fuel while on the highway, the leak must be infront of the driver. Am i correct in this assumption? I have already checked the charcoal canister and the lines going to it. everything looks fine.

any ideas on what to do next?

When we were in DC a couple of weeks ago, the check engine lite came on on our daughter's Saturn. Next time we stopped, I unscrewed the gas cap and tightened it down till it clicked a few times and the lite stayed off.