I see you as #7 in Google.ca (the web). But I can't find anything anywhere that identifies your site as Canadian, including in a whois. I don't know how you're ranking that well in a Google.ca - to be honest, that's the surprise to me, not your ranking in the US. Is this unique to that search term? What do you look like with other search terms?
You know, I haven't spent a lot of time looking at Google.ca results recently. I just checked a few search terms I'm familiar with and as far as I can tell the results from google.com and google.ca (web) are identical. You only see differences for "pages from Canada". I'm not sure what database(s) Google is querying for google.ca (web) these days. And again, I don't know why your site is different for google.ca (web) than google.com. Interesting. (Although that might not be the word you would choose ).
Similar results using different keywords. For example: sports handicapping .ca 12th position .com 115th position sports handicapping monitor .ca 7th position .com 20th position And another oddity... I have another website that has the exact same scenario. Using keyword "homework forum" we rank .ca 2nd position .com 17th position URL www.mystudentforum.com Simply bizarre...