I recently started taking suboxone while involved in a out patient program,I failed a urine test 4 opiates?

I recently started taking suboxone while involved in a out patieint program currently take 1 urine a week have not used herion in this time but my urine has come up with opiates twice already is there something in suboxone that would make my urine positive 4 opiates?

: http://alcoholdrugstreatment.info/i-recently-started-taking-suboxone-while-involved-in-a-out-patient-programi-failed-a-urine-test-4-opiates