Yes American-style, you are certainly right that Masterson's, plus Jefferson's rye apparently, are Canadian-sourced and aged in new charred oak, that is why it is okay to call them straight rye in the States. That practice though to release a whiskey made like that as a straight (not blended with other whiskeys) is an American one, in Canada they have not done this for generations. Generally in Canada, my understanding is the straight-type whiskey made in-house is used only for blending and generally too it won't be aged, or 100%, in new charred barrels, they often use in Canada (whether for the "straight" or blended products - let's call Lot 40 straight for present purposes) a mix of barrel types extending to reused bourbon and new (uncharred) oak barrels. Masterson's is an exception since you can buy it in Canada now, but it was sold in the States first and has an American theme on the packaging. In other words as I see it, Canadians don't see this kind of whiskey as something in general to release on its own (in Canada), that is an American practice.