If there is any leak in the vacuum, it will throw that code. Did you leave your gas cap off or loose? Did you get fuel while your truck is running? Any of these can throw that code.
You can crawl under your truck and visually look at the components. There is a vent hose that goes from your fuel door to the evap emission canister, well at least one of them. Then you can follow the other hose to the front of the truck for the control valve. Not hard to replace, I had to replace all of them on my '05. Just time consuming
If it's a small leak, you can reset the cel and it won't come back on for a few weeks. It won't hurt your motor at all, worse thing that will happen is that you will let some vapor in the air