How'd you get the pack? I guess that embargo we got for American products being sold (trolled) in Cuba is getting pretty lax.
Arcteryx is actually owned by Mountain Equipment Coop (MEC) - A canadian company
We don't have any problem trading with Cuba.
And For What it's worth, I've had problems taking 40L bags as carry on - it depends on the airline, you need to call them.
I usually put my backpack in checked luggage to avoid problems, both with size issues and the fact that I usually have a knife and lighter and other little things that carry on sercurity will not let me take on the plane. Often it's worth carrying a thin duffel bag to stuff the backpack inside so that the baggage handling equipment doesn't catch on straps and damage things.
Do be careful not to take stove fuel (gasoline, or canisters) on the airplane. That you will usually have to buy at your destination.