Gotta disagree with your math. Exchange rate today was 1.0847 CAD for 1 USD. NRIFF (American market) traded around $3.10 most of the day. NRI (Canadian market) traded around $3.35 most of the day. $3.10 * 1.0847 = $3.36. Pretty much on the mark.
Two reasons for the higher percentage increase on the Canadian market today:
1 - Canadian market closing price yesterday (Wednesday) was artificially deflated with a small trade at the end of the day.
2 - The USD had another very strong day against the CAD.