It shouldn't. Sometimes things cause strange drug test results, but I've never heard of anyone pissing dirty after consuming Kratom.
I don't think you could call it a false positive.... But I wouldn't think so, I think the chemicals are structurally totally different from the alkaloids found in opium poppies. They just do the same thing, similar to how JWH chems are cannabinoids as far as your brain is concerned, but are NOT if you use the natural structures of cannabinoids as the test. But don't listen to me, maybe it's an uber drug test....