Just a quick Q

I filled up on petrol last night and when I got to work this morning I noticed a fuel smell, so I checked out the tank and found a little bit of seepage coming from the filler pipe attachment point at the tank. Could this leakage be just because the tank is full (normal) or am I looking at a bigger problem with rust on the tank around the filler pipe? The tank is covered with dirt now but I will check into it further by cleaning the area with a wire brush and looking with a flash light.

Theresa the Toyota Terror-89 Toyota P/U (3.0L SR5, 5sp swapped in from auto, 3"B.L., 32X11.5X15 MT/R, 2.5" stainless magnaflow catback exhaust, leaky floor with cold draft @feet, FUBAR comptron now in glovebox)