96 (ranger)/(mazda B300 4x4)

I just filled the tank. I never top up and I've never had a problem before. But today, I started to notice gas leaking out around the tank while pumping gas. I immediately stopped the pump. Probably 3/4 cup of gas leaked out, and then stopped, down the side of the poly tank. There didn't seem to be any gas around the fill pipe. The tank was really filled to the top based on the gauge.

I'm just wondering, if the pump did not shut off when it should have, and there was too much pressure, is there some sort of valve that will open that might cause this release of gas? There have not been any leaks since the incident.

Any ideas appreciated!

thx,
rob