I think he needs to stop doing this because you don't feel comfortable at all, and it's important to feel comfortable and safe in your therapist's office. I don't know what his intentions are when he looks at your chest, someone said for breath checking but it seems like this happens everytime so I doubt that he wants to check your breath every second/minute. You should explain him that you feel uncomfortable and you want him to stop looking, you have all the rights to say this to him. Maybe he doesn't realize that you are feeling uncomfortable. I hope that you can tell him this and that he stops doing this!