Just a thought.
The metabolite is stored in fat.

Did you do any heavy lifting the day before, or running, exercise, fasting?
Anything that causes your body to burn fat will raise the concentration in the urine.

If you have stayed clean, you might want to challenge the results.

Tell them it is simply not possible because you do not use "drugs", and ask for a retest.
That's an honest statement, it's an herb, not a drug.

Either way, best of luck.

Aloha,
Weezard