Drpower

A few months ago I got a check engine and after using techstream it showed that it was from both upstream sensors. I unplugged the battery and even erased the codes but the check engine came back on. I went ahead and ordered both O2 sensors. Weirdly, two days ago I had a blown fuse and changed it. I didn't drive the car until today when I noticed the check engine was gone. Now I have a dilemma of just leaving it the way it is or going ahead and just replace them since I have brand new ones. Should I change them now that the car has 120K?