Your customer is trying to see how broad your shoulders are. That aside if any of your customers have pets someone will get the blame, and in spite of your best intentions it was your turn. Very rarely have I ever know responsible and pet owner having much to do with one another. I would make an attempt to contact her and make sure her dog is ok and than see if anything else can be done to solve the gate issue, if there is one?
You not admitting any guilt just concern.