If you poked at the chrome with the X-acto knife and got a hole out of it, then the metal has rusted away to nothingness from the inside. My thoughts are rough handling in transit was the straw that broke the camels back exposing the invisible. I am hesitant to lay blame with the seller in this case.

Had the seller taken proper precautions with shipping you would be riding a ticking time bomb and never known it. Given the seller compensated for shipping damage already, I take that as a good faith effort. It sucks that it turned out to be a bad egg.