I think you would have been notified already and given a chain of custody form if they wanted to do a drug screen. Otherwise it is not a pre employment drug screen anymore. It will cost Wells more problems and possible legal headaches to perform a drug screen on you after a job offer is made and accepted by both parties. Pre employment drug screens are made with a "contingent" offer of employment. The offer becomes valid after the applicant passes the drug screen and/or any background checks.