I also had traces of blood in urine. Had it checked out via an ultrasound and given the all clear. Apparently, the dipsticks themselves can give a false positive reading due to the chemicals on them!! As others have said here, can also be due to exercise, eating certain foods...even drinking water before your medical, just so you can produce said specimen in the first place!
Try not to worry too much....it's probably nothing more than a slight infection, and in any case, you're getting it treated quickly.