Canada has had terrorism within the country since the 60's & 70's. Not on such a massive scale as 9/11, but they've had to deal with it for quite some time. They have had an anti-terrorist squad for many years.
I think a lot of the public in Canada feels a sense of "they won't come after us". I think that will change rapidly as the Winter Olympics in Vancouver will show. Security will be unbelievable, and the assholes will look towards the olympics as a "splashy thing to destroy".
A Lot of Canadians have forgotten, or are too young to remember the terrorism in the 70's, gunned down diplomats in Ottawa etc... they had some shit going on back then.