Owner Accusation

I just watched a dog that was picked up today and I received a message asking if I musseled their dog. Like I said, I don’t own any so I’m not sure what could’ve caused the marks. I also didn’t notice anything myself the whole time he was here including at pickup time when I put his harness on him. Did I handle this okay? I’m a bit worried about getting a bad review when I didn’t do anything wrong.