Quite possible. Marijuana tends to accumulate in fatty tissues so may show up for a few weeks or longer in a drug screen, depending on the amount and duration of smoking.
Could Be Detected. The following data is taken from www. Canorml. Org. Marijuana - single use: 1-7+ days in urine and 12-24 hrs in blood. Marijuana - regular use: 7-100 days in urine and 2-7 days in blood. Note that urine tests do not detect the psychoactive component, thc, so in no way measure impairment; rather, they detect the non-psychoactive metabolite thc-cooh, present days to weeks causing no impairment.