Hot Gas Tank

[Overkill]

I took my Camaro on a road trip yesterday that lasted for about two hours. It was the longest trip that I had taken it on. Most are half hour to an hour. When I got home after the two hour drive, I noticed a weird sound. It was a low hiss that I tracked down to the vented gas cap on my gas tank. I slowly removed the cap and it sounded as though the fuel in the tank started to boil. Needless to say, that scared me a little. I touched the bottom of the stainless tank and I couldn't hold my hand there for more than a couple of seconds. There isn't any source of heat close to the tank, my exhaust dumps in front of the rear axle and isn't closet to any fuel lines. The only thing that I can guess is that my fuel pump is circulating the fuel so much that the gas isn't cooling off in the tank like is should. I run a MangaFuel ProStar EFI 600 pump that is rated at 850GPH. I bought this pump so that when I do twin turbos in the car I wouldn't have to buy a new pump. Am I thinking right that the fuel isn't allowed to cool off properly and also that the vented cap and the vent in the top of the tank aren't big enough to relieve the pressure, which is higher because the tank is so hot? It's definitely only going to be short trips until I can figure out what is going on.

I guess if I put cooling fins on the gas tank I'd have a second radiator.