How did you undergo medical examination without a request for the same from CIC? The medical examination you underwent in November, 2011 was not because of a request, was it? In that case, you need to take the test. I have no clue why the lady misinformed you like that. Are you in Canada? And, if yes, did you take a medical test as part of your entry to Canada?
What does your PPR letter read? Is it asking you to go for a medical test? I would suggest you to provide all the information that you're required of. Perhaps, that's the wisest and safest thing to do.