Recently, there have been many complaints about the exchange rate used in Canada by Google to payout AdSense publishers. A DigitalPoint Forums thread says the rate was 1 to 1, calling the US dollar equal to the Canadian dollar. Plus, Google charges a fee on top of that, according to the thread.
But it seems like Google is making a change to that Canadian exchange rate.
The email sent to these publishers said Google used an "incorrect exchange rate" for Canada. The WebmasterWorld post said:
Did anyone else receive a notice from Adsense about being issued a payment with an incorrect exchange rate? Apparently they're going to issue another payment to correct this. I remember that this happened before last spring and they recalled a whole bunch of EFT payments and reissued the corrected versions immediately. I'm in Canada, by the way.
This is not the first time Google reissued payment due to exchange rate issues. Google inverted the Australian exchange rate and had to reissue payments in the past. Plus, often publishers complain about the exchange rate Google uses.