custom2002

Need help My 1989 C4 Corvette is in the shop for a fuel tank replacement. I put a new locking gas cap I purchased from Amazon an AC Delco after market? cap. I drove about 15 miles heard a noise that sounded like my hatch release opened. After checking I found my gas tank had moved. And had a large indent on the passenger side and it looked like a strap had broke. After I took the car to my mechanic he said he never saw anything like that. He thought there was a vacuum issue. After he told me he checked the gas cap ( I put the original cap back on before I took the car to him because it was tough the get the locking cap off because you needed to get the key into it and it took some effort and I didn't want him to have to deal with it) When he mentioned he checked the gas cap (original) on the car he said the venting was fine.When he said that I told him I had just removed the locking gas cap I put on. Could that be the cause? Now I need a new gas tank because we are concerned I may develop a leak at a seam. Very expensive replacement. Does anyone out there have any ideas. Could my locking cap be an issue?