On every FedEx international waybill there is a box to be checked as to who is responsible for duties and taxes. It is on the right side of the form. Next time make sure you check "recipient" and you shouldn't have to pay.
Problems with shipping to Canada
I checked the Forums but this topic doesn't seem to have been addressed before so potential shippers to Canada take heed. In June I shipped an item to Canada by FEDEX where the buyer had agreed to pay shipping and be responsible for paying the import duties. However FEDEX has been unable to collect the fees from the buyer and have informed me that as shipper I am ultimately responsible for payment. Luckily the amount I'm out of pocket is not large ($120) but I just wanted Agoner's to be aware of this possible pitfall especially if shipping high-value items