Not sure, but this may be a new policy by DC, and the others, to combat cross border new or like new truck sales. It also may be their annual rolling update of the policy, i. e. last year it excluded 02' models.
All the manufacturers get upset if a new Canadian sold vehicle is registered in the US before a certain date after purchase. Last I heard was 4 - 6 months or 15,000 km, which ever came first. If your after one or other of those limits, then I understand that the manufacturers have no quarrel with a resale and will, or did in the past, honor the warranty. Course, when I researched this last year, there was no talk of not honoring warranties, just punishing dealers.
Vehicles are priced for the Canadian market, and with the exchange rate, we pay a lot less for a vehicle than you all do in the US. Good used low mileage trucks don't exist in many parts of Canada. You can buy a truck up here, particularly a diesel, use it for awhile and then sell it into the States for more than you paid for it in Canada. Most just sell to exporters, but those who do it themselves can make several thousand.
When the PC Cruiser first came out, the dealerships in Canada were on high alert to ensure that the purchases by Canadians were "legit". The short supply, high demand and low dollar meant that Americans were willing to pay a relatively generous premium (from the point of view of a low Canadian dollar) for a Cruiser. A Canadian buying one and then immediately selling it to the US could net, it was rumoured, more than $10k Canadian. So the dealers, if they thought the person was buying for resale of any type into the US, wouldn't sell to the person. Its the dealer who gets penalized if it happens too often with vehicles that the dealer sold. Now maybe DC (and the others?) have decided to punish the individual owner too.
Any warranty problems inflicted upon the vehicle purchaser, particularly a good faith purchaser in the US (way to go DC... that's sticking it to the vehicle owner), may be actionable. Then again, maybe the easy solution is to purchase aftermarket warranty coverage that makes up for DC's customer service decision... oh... wait... I am Canadian... DC is... well its... that can't be... is DC trying to protect Canadians from themselves and the US high prices. Course, if our dollar ever comes back, many of us will do what we did before it went into the toilet, buy US. There aren't enough of us for DC to worry about that then... too many of you all now though trying to buy the other way.
Attention: TDR Forum Junkies 
has has climbed enough to eat a fair chunk of the profit margin.
