It depends on how well your immune system is keeping the infection at bay and limited to only your urinary tract. That may change very quickly if you become ill with another infection, or if you take a medication which "distracts" your immune system. That said, you should seek medical attention for abnormal urine signs even if you don't have symptoms. You really don't want your symptoms to begin when too much damage has been done or the infection worsens into kidney infection or worse.