Cannabis withdrawal syndrome (CWS) isn't real, it's a myth. The studies that claim to find this, actually induce percipitated withdrawal in rats where they were given SR 141716 aka rimonabant at the same time as THC cessation and these side effects were erroneously recorded as that of cannabis withdrawal.

Cannabis binds to receptors in fat, and when a user stops use, the drug is slowly released into the bloodsteam from fat like a time-release vitamin. Fortunately, this means, that there aren't physical symptoms of classic withdrawal, but unfortunately this also means that cannabis can be detected in your saliva, blood, or urine, long after you've last used.