Owner gaslighting

Hi, how do you handle owner gaslighting? I had a very weird interaction with the dog owner today, just before starting my housesit with this returning client. I mentioned giving treats to the dog to distract him when I’m in a meeting (owner knows I housesit around my 9-5) as he often barks. Their answer was “Ok interesting - he doesn’t usually bark randomly very often without something triggering it. Thats weird! And imagine annoying during a meeting”. I’m at the house now and the dog has been barking while I was cleaning his poo (yeah, anxious dog, owner left him alone 30 minutes before my arrival and he took revenge), while I was washing one dish and any time I wasn’t giving him my full attention. I cannot believe he doesn’t do the same with the owner and I feel very much gaslighted here. How would you handle that?
He’s a lovely pup, I enjoy looking after him overall, I have lot of clients and can afford to let him go…
What would you do?