I don't think there is any evidence for mental reflection at this moment, but the nature of reflection is that is entirely internal, and we don't really know in what manner dogs have cognition.
But, the trend seems to be that we only learn more about the inner lives of animals as time goes on. 100 years ago it was accepted that non-human animals were essentially automatons that didn't feel feelings or have emotions, or engage in any kind of thought, which we know now is not true.
