This may sound funny, but will happen if I test positive for PCP upon returning to BCT?

haha I know I know! I did not use PCP (or any drugs for that matter) but I have a nasty chest cold and have been taking over the counter cough medicine, and I found out that one of the ingredients can produce a false-positive (whatever that means) on a urine screen for drugs. So will they be able to see that its cough syrup and that Im not a druggy?