I've come across people that were mildly confused. Even with non-trivial amounts of exposure to American language-isms/culture it's still possible to over-look the nuances. There are probably a lot of instances where the context doesn't allow the listener to make the distinction between whether the 'Canadian definition' or 'American definition' of the term is being used (unless you're <i>really</i> paying attention for that sort of thing; like if someone told you to pay attention to it).