Need help with O2 sensor
 

I searched here but couldnt find any similar situation. So I got my oil change from the dealer, but a day after I had check engine light on. Back i went to them and after checking they said apparently tech spilled oil on sensor and hence would need to be replaced so they said they will order the part and call me when it arrives.
Well couple days later the light went off and now when I went back to dealer. They told me that the light is not on and no error codes so its not necessary to change it, but they would change it if the light comes on again and they would give me a written warranty.

So my question is should I just listen to them and take the car back.
Or push on to have it replaced.
Thanks for any adivise.

that doesnt sound right though. a light for o2 sensor going off because of some one spilling oil on it. something fishy going on here.

If they give a written warranty I wouldn't sweat it.