I had the exact same thing happen, when we bought our new to us 2000 Pace Arrow and bought gas the first time, I noticed a leak from the fuel filling area, so shut the pump off and checked sure enough it was dripping. Went in and told the cashier and she gave me some spill absorb and told me they would clean it up later. Drove the rig home(January and 24 degrees). Looked under the rear and located the fuel filler hose, measured the piece that was leaking and went to the local auto parts store and got a 12 inch piece and 4 heavy duty hose clamps. Installed the hose with the two clamps on each end and no more leaks. Most likely it was a type of hose not meant for fuel or an old new stock that wasn't made for unleaded(there is a lot still around). The one I removed had no wire coil in it and the one I did had the wire in the sidewall of the hose. Be sure when you replace the hose, it says for unleaded fuel. If you can find it and want to pay the price, marine fuel hose is the best, but costs a lot more than automotive..
2000 Pace Arrow 33v
10 Kia Soul-05 HD Ultra Classic