well first off at least they told you and didnt try to cover it up,so that right there shows integrity on there part,i wouldnt worry about any issues further down the road,if its a reputable shop im sure they have it on there frame stretcher if there was any main frame damage,but if it was just a lift arm that slid out it most likley just damaged the door as it went in the air,i would trust that it was a mistake per human error,and that they will do there most proffesional job repairing it,cuz if they cant satisfy a customer with free repair work why would he come back to pay for any other repair work,hope that helps,goodluck.marc