What Causes Blood In Urine While On Aspirin?

I am on a daily low dose aprin and my gyn tested my urine at a regular exam which shows blood in urine. She told me to stop taking asprin and recheck urine in a week to see if the asprin could be causing this. Is that enough time for the bayer to be out of my system so that if that is the cause my urine will be clear of blood in a week?