2002 Honda Accord Crank Sensor

Dear Sirs,
Recently (3-10-10) I had the timing belts water pump and front seals replace on my accord. While my wife was two states away it began to make a horrible noise and she was able to make it to a repair shop. They informed her that the "crank sensor" was not properly torqued and had failed.

If I understand correctly the crank sensor is important to determine TDC. But since the timing belts where all replaced would the previous mechanics be responsible for the proper placement and security of this part?

I know parts fail without warning, that is just mechanics, but will I have a leg to stand on if I go back to my mechanic and ask if he warranties his own labor?