I took the LS3 Z28 out for a drive today and notice my low coolant light came on. So I took it back home and when it cooled off, I opened the radiator cap to find that the radiator was still indeed full. I cranked it and ran it with the radiator cap off and got some bubbles and a very light foam on top of the coolant surface. I shut down the motor and went back to the engine bay and hear a long -- 'sssiiiiiiiiiiiiiiiiiiiissssssssssssss' from what sounded to be coming from the passenger side head area. I'm alittle worried my gasket may be cracked enough to let air in. Does this sound logical?