05 Colorado new rotors and ABS problem

Hi - My husband brought his 05 Colorado 4wd to a local mechanic for a brake job yesterday. Guy quoted him approx $1,000 to change brakes and rotors; seemed expensive. I did a net search and found that on this truck it is indeed an expensive job. Husband OKs the work. In my search yesterday, I recalled reading about a subsequent ABS light problem some had after replacing rotors and off-handedly mentioned it to my husband.

Today, mechanic calls & says brakes are done....but now ABS light is on. He's ordered a new sensor (no quote on that yet). I am so annoyed as after reading several posts on the net, it seems this is kind of a well-known problem.

I found post on another forum where the poster said he followed another fix to tap the ABS sensor closer to the hub. I've printed that out and am going to bring to the mechanic tomorrow.

But my question is this: did the mechanic cause this problem? Should he have known better? If the tap fix does not work, I am sure he is going to try & pass the cost of the sensor (and possibly the hub if I understand other posts correctly) onto us. And I want to know if I should say "no, you caused this".

Thanks for any advice or input you may have.

Cindy