Duster 340 oil pan

I don't remember the stock pan on my old 340 Swinger having that 'dimple'. That looks like it was hit by something - and not at the factory.
My current '69 Dart has a similar 'dimple' on the bottom of the gas tank and I can't figure out what caused it. My gas tank almost looks like the car had to have been dropped on something because the dent couldn't possibly be caused by something that hit it from the side. Oh well, it'll be gone when the new tank goes in.