P0456 and P0442

2003 Nissan Frontier Pickup Truck...Two codes showing...P0456 (Very Small EVAP Leak) and P0442 (Small EVAP Leak). I replaced gas cap, erased codes, and light came back on after driving 25 miles. Same two codes appearing. Checked all my hoses and connections under the hood. All seem OK. I seem to be smelling gas fumes near the rear of my truck on the filler side after I have driven it and parked. I did take a quick peek and there are no visible signs of fuel leaking. I did replace the gas cap with a genuine Nissan one to no avail. I do have an appointment at the dealer this coming Monday but would like to see if I can fix this myself this weekend. Something tells me it may be something very simple...hose, clamp, connection, etc. Any ideas or has anyone else run into this problem? Thanks.

Check the filler tube gromet/seal located on the fuel tank itself. The tank also carries caps on the tank. The fuel doesn't need to leak out it evaporates and vehicle is able to detect a leak.