Was the shipping done through the Global Shipping Program?
Did the tracking show the seller sending the parcel to Erlanger KY?
If so, you paid import fees when you paid for the item and nothing more should have been collected at your door.
However
A lot of sellers were enrolled by default in the program and did not realize it.
Those sellers (who can't see the GSP information on their own listings. Seriously. And yes it is dumb dumb dumb.)
will ship the way they normally would, using USPS.
Then when the parcel arrives in Canada, Canada Post will charge the recipient (you) the import charges that neither Canada Post nor the seller realizes have already been paid.
Sigh.
And that's why we need more specific information.