I need some opinions on this situation...

I am dog sitting for a neighbor who went on an overnight vacation to vail, invited by some friends. These are big dogs. David, the owner rescued both of them. He paid for an expensive surgery to fix the female’s leg. The male, “Rupert” had been very abused by the previous owner and doesn’t like people. It took him several times seeing me and being in my house for him to trust me. He used to bark at me. Last night I was walking the dogs a guy was coming toward us and Rupert, the male was barking like crazy. The guy kept coming. I had both big dogs AND my little Katie (who was not on a leash) They were pulling me and making me run. I was pulling back because I didn’t want to run on my damn swollen twisted ankle. As he got close enough for me to hear him, he said, “whoa”. Just after he passed us, he turned around and said, “that one bit me.” No alarm in his voice at all. I turned and looked at him but he kept going and turned into his apartment. I continued walking them. A minute later he came back out, walking toward me and said that he saw his leg was bleeding and asked for my name and apartment number. I was so stunned—I just said, these aren’t my dogs. I’m dog sitting. He said that he hoped the owner had gotten them their rabies shots and I said, I’m sure he did…he put himself in debt over the female’s leg surgery. Now he thinks he needs a tetanus shot—that doesn’t make sense. That’s just for metal, isn’t it? He never showed me a bite mark. I feel bad about it. I talked to David, the owner, this morning and I didn’t tell him. I’ll tell him this evening when I come home. I never even showed concern for the man, I was so stunned. Now I feel like a heartless idiot.