I have never heard of this
Until recently you could conduct business in both Canada and Mexico using the dollar. Short of the rapid decline in the USD to CAD I would think that it would be much easier (logistically) for Mexico and Canada to just use the dollar as their currency. If you compare the GDP of the US to that of Canada and Mexico it would not make much economic sense to start a new currency. The US’s GDP is still 6 times larger then Mexico and Canada (combined).