Good point. I didn't see that. When you throw in Canada's tar sands, it's a lot less surprising that North America could be a net exporter in <20 years.
I believe Mexico figures in those calculations also. According to this field they have large reserves, though extraction is expensive (like oil shale and tar sands).
"By around 2020, the United States is projected to become the largest global oil producer (overtaking Saudi Arabia until the mid-2020s)"
So maybe that part of the story is overblown. But perhaps more interesting is that the US will supposedly become a net exporter shortly thereafter:
"The result is a continued fall in US oil imports, to the extent that North America becomes a net oil exporter around 2030."
Source: IEA World Energy Outlook 2012 - Executive Summary http://www.iea.org/publications/freepublications/publication... [PDF]