Gas expanded and overflowed over night?

Not a vent problem, no vent problem could possibly cause that. I think the OP had it right. Maybe you just got "lucky" and got a nozzle that has a poorly operating shut off, and somehow just filled it quite full.

EDIT LOL I was not thinking. A PLUGGED vent could allow this problem to happen, but the vent would at least allow the fuel to spill out on the ground, rather than all over the paint/ out of the filler.

What is the temp difference from the gas station to your garage? Heated garage?

As "tall" as the fillers are on Barracudas and even the other A bodies, that doesn't happen often. I've owned 3 B bodies, a long time ago. The fillers on them are barely above the fuel tank "roof"----out behind the license plate. I used to "wash" my rear plate quite often.