I freaking love it when people say "thank you" as their marker! To me, it just shows how much stock they put in the intelligence of their dog and how deeply they respect the relationship they have. Language impacts how we manage aspects of our lives and small things like this build on themselves to awesome results.

We use "thank you" as our low key marker - rewards are settling activities like scritches or a chew toy, or sometimes pushing the cat out of his bed so he can use it. Our high energy marker is "wow" because it's easy to say in a happy way but not something I say all the time.

Do it! Your dog will absolutely pick up on the fact that you're having fun interacting with them.