I took a drug test and tested positive for xanax. I had a prescription for it from Sept. 2011, and still had some left and took some the day before my drug test because i was nervous about my job interviews. WIll ifail my drug test because my prescription was from sept. 2011? i thought the prescription didn't expire for 1 year? i am just worried that they will fail me for a 7 month old prescription. PLEASE HELP!!!!