It depends on the inventory that Canon has, and that the dealer has. If Canon has 5 months Inventory, and the Dealer has 2 months of inventory, the lens might be from last fall.
My 16-35mmL that I bought last July from Newegg had a October 2011 date code, or about 7-8 months old. I'd suspect that's typical for a high end lens that is not a popular new model.
I have bought new lenses that were only 3 or 4 months old.
It would be possible to find one with a 2013 date code, but unlikely, Canon makes lenses in Batches, so you'd have to hit a new batch where the dealer was out of stock and just received them.
For slow selling lenses, a year or two is not uncommon.