Here's a link to an article about increased security at the Canadian border.
We go to Canada often, for both caching and general shopping. We've have noticed recently that, in addition to the usual driver's license check and the wquestions about what you've brought back, they take our driver's licenses into the building and we wait about 5 more minutes. Evidently the "background check" has been going on for some time.
But the wait is minimal, and we STRONGLY encourage you to try caching in Canada for a change. There are some really interesting sights and history.