Today is 12/18/12. I smoked pot twice in October, maybe a total of one bowl, probably less. I smoked a joint on the day before Thanksgiving and took 3-4 hits (something called purple cheese). Now, 27 days after my last smoke, I am selected for a hair test. Had my hair cut today. Did not do anything to try to "wash it our of my hair". Is there a chance I passed due to the infrequency of smoking?