Ninja,  If that were the case, though, I would think the Draught and Extra Stout would also say "Product of Ireland" rather than "Product of Canada."  I certainly agree with your thoughts regarding the supply chain; Jamacia is a lot closer than Dublin.  Perhaps the Jamacia plant doesn't have enough capacity for the US volume?  Anyhow, it's not terribly important as long as it tastes good.  
Cheers!   
 
I want one of those goblets, too.  
