I have a Kenmore Deluxe Demand Water Softener that is approximately 12 years old. Lately, I've noticed that while the master bathtub is being filled, the water softener discharges water to the overflow drain. I don't know if this has just started occurring or perhaps I just never noticed before... at any rate, can anyone tell me if this normal or is it indicative of a problem that needs to be corrected? Thanks!