I felt kind of bad when Aaron was so quick to compliment me. It turned out that the person who signed for his package had to pay a substantial fee. I went to my shipper, paid for simple UPS ground, declared the item as a gift (they told me this would mean Aaron's mother, the recipient of the package, would not have to pay taxes on the package), and sent the thing off without giving it a second thought.
I called my shipper when Aaron contacted me and they told me UPS calls the fee he ended up paying a "CD Brokerage fee," something listed on the receipt under "import tax." I was never told by my shipper that this was a possibility. I've never had to ship anything IN to Canada before, either, so I suspect this is ignorance on my part as much as anything else.