I don’t disagree with @Tester very often, but this is one thing I do not agree with him on. Modern cars are required to have roll over protection gas tanks, that is in case of a rollover, there are flaps or valves that prevent fuel from escaping out of the gas tank and feeding a fire.
They theoretically should prevent a tank that is overfilled from allowing fuel to enter the canister, however the vibrations and bumps you feel going down the road allows gas to enter the emissions lines and can cause this issue. If you stop overfilling, the canister will dry out and the problem goes away.
Some cars, i.e Subaru’s (new models) can also suck water into the vent lines through a filter. This can happen when you drive through a flooded street or road. 3 or 4" deep is enough on some models. This does not dry out the same way and requires a very expensive repair. I don’t know if your vehicle is prone to this or not.