s in the urine usually mean infection, but other things can cause it in small amounts.
Frequent sexual intercourse, masturbation, dildos, vigorous sex all can cause a
small amount
of WBS occasionally.
However, if this is a recurrent thing, then it should be investigated. I would start with a gynecologist, and if everything is normal and the finding persists, then maybe a urethroscopy and workup by a urologist.