That is weird. I understand that most medical schools don't even give their exact MCAT cutoffs. One reason is that they do not want to give the wrong impression to applicants; they just want the quality of applicants to their school to be as competitive as possible. Another reason is that depending on the pool they get each year, their standards may inch up or go down year to year. And with that WS cutoff, usually most medical schools in the United States (I am not positive about schools in Canada) do not put much emphasis on it since they will see a writing sample in the form of your AMCAS personal statement and if they require them, essays on the secondaries. They will, however, be hesitant to accept you if your WS score is lower than an M or an N (the average). I would take the information that you got as a grain of salt. Even if the person who told you is an adcom member, I would strive higher than what they say in order to be safe. Good luck with everything!!