Hello 'tonsnide-0',
Many things could cause it. First of all, are you sure that the seller ships to Canada? Sellers can block buyers who live in a country not on their "ships to" list.
Or it could just be a weird ebay 'glitch'. These happen quite often, when we want to do something and get a pop-up message saying it won't work. When we try again it is fine.
Have you placed multiple bids on many of the seller's items? Sellers can restrict the number of items a person can buy at one time. Sometimes when that happens a buyer must send a note to the seller explaining all the items she would like to buy, and ask the seller for an exemption to complete her purchases.
Or sadly, perhaps it is merely because you have a low feedback score. Sellers are really prickly about new users, and I have even seen listings which state "If you have a feedback score of less than 10 your bids will be removed". Sounds terribly unfriendly, but too often new people do not know how ebay works and thus will win auctions and not pay for the item.
When you buy an item or win the auction, you are expected to follow up right away with payment. Never bid or buy if you are not absolutely committed to paying for it.
So perhaps your seller had a bad experience lately and is still smarting over it.
If the auction is still open you could always send a sweetly worded note to the seller explaining the message you received, inquire if he knows of any reason for it, and say that you would like to continue bidding if that is okay. Let him know that if you win the auction you have every intention of paying for it promptly.
Good luck 
