I had a funny "gotcha" :-) 9 years ago, Ed and I had just crossed from the lower US into Canada on our drive to Alaska, when my credit card was refused at a gas pump. I ended up having to call the CC company, where a nice young man (who certainly sounded "American") answered.
I told him that a week prior, I had called and put a "travel notice" on our credit cards, that we were driving to Alaska from Michigan. He asked "Are you driving through Canada?" *I* asked "Do you have an alternate route?" There was a long pause, then he burst out laughing. Didn't have any more problems on our travels :-)