thanks for the responses. Just felt that I should provide an update to my situation. I just received word today that my drug screen cleared, huge relief. I probably won't be smoking again until I am certain that they don't do random screening.

Also, for future reference, the minimum threshold is 50 ng/ml, though if there is reason to be suspicious or if it comes up positive then a more stringent test is performed which has a minimum threshold of 15 ng/ml. From what I've seen online, it seems that recreational smokers like myself usually pass the first screen just fine, but the second screen is low enough that it can catch people for frequent/prolonged 2nd hand exposure.