I can understand worrying. I worry all the time about stuff, but I think that even if your therapist was annoyed by your carer's attention to the dog, she wouldn't blame you for it. Probably she wasn't even annoyed by it. After all she does therapy at her house and she has a really cute dog, she has to expect that people will want to pet him. And she could have just ignored your carer talking to the dog through the window.

I really would try not to worry about your therapist's feelings in this. She should be able to handle them herself and set boundaries if she feels she needs to. And you aren't responsible for your carer's actions. Any reasonable therapist wouldn't think you were.