As a Rover service provider, what should I do if I see symptoms that indicate that a dog should be evaluated by a veterinarian soon?

As a sitter, I have noticed that a repeat client dog has ongoing symptoms of pain such as panting, trembling, occasional vocalizations. I love this dog and I appreciate that her owner is confidant about my care of Daisy. How do I delicately suggest that Daisy needs to have these issues and some abdominal lumps and bloating evaluated by a veterinarian soon? I don't want to seem critical of the owner's care. Daisy is over 12 years old and it may be that her owner hasn't noticed changes because she is accustomed to seeing the dog every day. I want to look out for Daisy without over-stepping my role. How do I do this?