How long will hydrocodone stay in your system for a mouth swab test?

I took a saliva test for a job screening. They do test for it specifically because I had a script for Tussionex, drank 40 mg amount in the AM, got the swab at 1 PM, and it was detected. I didn't care cus I had a valid script. The service called me, I told them I had a script for Tussionex, and he said good and that I had 5 days to fax the info. So don't think a saliva test will detect only real opiates like morphine and codeine. They can also detect the semi-synthetics.