Just to wrap this up cleanly.
Fedex had contacted me because they were trying to "pre-clear" the box through customs. IE, trying to get the box cleared customs BEFORE it actually arrived at the destination port.
I don't think "pre-clearance" is _required_, but I think fedex does it when they have to turn a package around quickly to send it back out on a plane.
I believe my package failed to be pre-cleared, and as a result, missed the outbound plane -- and so was cleared normally (and customs had access to the physical box, and the FCC form) It shipped out on a flight the next day, which meant it was delivered to me a day late. No big deal.
Incidentally, I think amigakit is using an old Harmonized Tariff Number, because the current HTS does not list the number they are using. A friend of mine, who does this stuff for a living (who is also technical) said that they likely should be using "8471.49.0000"
http://www.usitc.gov/tata/hts/ (if you are really bored...)
FYI if anyone runs into it