If I had this happen to a second-hand gas tank which I bought off of someone, I would have taken it to a radiator shop in mid December and be done with it.
I for one will not be spreading any negative words about a company that has gone to great trouble to design a tank which is near impossible to tell it from an original tank, and sells it for less than one must pay someone to clean and seal an old tank.
But that may just be me.