This was issued in the US, I'm not sure if it is applicable in Canada.
http://www.prnewswire.com/news-releases/top-fin-plastic-aquarium-heaters-recalled-by-petsmart-due-to-electrical-shock-hazard-300102054.html
That's a lot of heaters!
Hopefully, if they were sold in Canada, there will be a issuance of this recall here, too.
If you follow the link to the Consumer Product Safety Commission, it mentions that Canada is affected and that there was a similar recall back in in Aug 2014. :o
http://www.cpsc.gov/en/Recalls/2015/PetSmart-Recalls-Top-Fin-Plastic-Aquarium-Heaters/