Do I need a lawyer for this an what should I do

I recently sold my car an the buyer got the car impounded for not having a valid drivers licence. The impound lot sent me a notice for the 30 day impound fee because he did not regester the car in his name. I notified my insurence company an turned in the release if liability to the DMV 2 days after I sold it so I am no longer responsible for the car. Right? What can I do an what should I do to not get charged with the 1300$ or so fee it's going to be.