I have had some bouts with kidney stones and now my dr says there is trace blood in my urine. Should I be worried?

No point in worrying. Trace blood most likely might indicate residual stone fragments or a new stone, might indicate bladder tumor, if ur a smoker or kidney tumor or hopefully means nothing other than an inconsequential trace of blood. Kidney & bladder ultrasound is a reasonable screening study for stones or tumors, although tiny stones can be missed. Best discuss it with your urologist. Have u had a metabolic work-up?