BUYER BEWARE! FOLLOWING THIS ADVICE COULD LAND YOU IN BIG TROUBLE!!! While what you did from a Canadian perspective is fine, from the American side of things what you did is illegal and could land the person/dealer you bought from in big trouble. American dealers must ship from an FFL to an FFL (e.g. Prophet River) and you must have an Export permit from the United States which the FFL will provide. That goes for scopes, rings, bases, rails, bipods, etc. Basically anything that is a firearm or firearm accessory.
Same goes if you travel to the states. You can buy a scope down there yourself and drive it across the border. Declare it like you would anything else and you're good to go. Problem is if you get stopped by American border patrol on the way to the border and they determine that you're exporting a scope and you're in big big trouble.
See this thread from
Hunting BC for an example of what can go wrong.