HELLO AND WELCOME TO HCM,
in urine should have some concern. But after coming positive in urine, clinicians usually advise to do a blood bilirubin
to rule out any liver
As your blood bilirubin is normal, there should not be any concern of a disease.
Since urine examination is done on analyzer which functions on a prinicple of colour change, it can give false positive results.
So, you should not worry and repeat a urine examination to check whether the urobilinogen is consistently present in urine. And please ask the laboratory to confirm the positive result by manual method also.