stopped payment on check

My father had some work done on his car while he was visiting me from out of state. When I took him to pick up his car, he asked me if I could write a check to the repair shop for him since he did not have his checkbook with him and he would deposit funds to my account the following day. I wrote the check. Later that day, on his way back home out of state, my father's car broke down as a result of the work done by the repair shop. My father told me to stop payment on the check and he would discuss the liability for the service bill with the repair shop. Apparently they did not work out their problems as the repair shop is now threatening to sue me for stopping payment on the check. I looked up the Oregon statute (ORS 30.701) and found that it only applies if payment was stopped without good cause. I feel that I had good cause. The debt was not mine. I did not assume the debt by writing the check. My contract was with my father, not with the repair shop. When my father breached our contract by not depositing funds to my account, I stopped payment of the check. I believe that the repair shop would not be able to prevail in this action against me. Am I correct? Help!