El Steak figured out what caused the damage and sent pics. It was the cranks grinding against the downtube. As you can see from the picture below, the damage was to the downtube, and the leftmost mark has the dent.
I pack every box the same way, with the cranks wrapped in thick cardbooard and heavily taped, and firmly packed in the rear triangle of one of the frames. I also put loads of paper between the cardboard and the frame to prevent chafing. When I ship, the downtube is packed flat against the bottom of the box and simply can't move from that position on its own, there is no way for anything to get underneath it.
So it looks like the astute customs folks took the stuff out, jammed it back in with no regard to the contents, and decided to make El Steak pay extra for the pleasure. It really frustrates me to see good hardware damaged by incompetence, and frustrates me more to see my packing effort wasted by some bureaucrat chasing down $70 worth of revenue. I hope he can press a good case against Canadian customs for damage. However, while it is not pretty, it is still a viable solid frame.
El Steak said the replacement frame was unneccesary, but I still felt bad that he did not get it in the condition that he paid for, so I refunded him the cost of the 2nd frame and a little bit of shipping. I'll continue to ship to canada, but require that the parts be shipped in a second box. Domestic US shipping should continue to be fine.
PS - No, I will not be raising my prices to match the valuation assigned to them by Canadian Customs
these frames are too pretty for their own good!