Hi! So this is my opinion, coming from someone who has quite a crush on their therapist and tries very hard to be mature about it. If you want to say something to your T about his sobriety date, I think that I would suggest waiting until you see him and then at some point saying something like, "I really appreciate how you shared with me your own sobriety date and that it was so close to mine. It made me feel like you identified with me and understood me, and it helped me to feel less alone. I was thinking of you on your sobriety date recently and wishing you all the best. [And you could mention how your sobriety date went for you.]"

I feel like mentioning it when you see him might be a little more casual then emailing him about it that day, but I suppose that it really depends on your relationship. My T knows that I have a crush on her, she's handled the situation well, and I don't think she's uncomfortable about my feelings for her... but I definitely would not be comfortable giving her a flower arrangement, and I wouldn't feel that it would be appropriate for me to do so. So I think that you have a different comfort level with your T, and since we don't know you/your T/all the details, we can only give general advice. And I think that most all of us on the forums just generally worry about both therapists and clients being respectful of each other's boundaries and that the therapeutic relationship is actually helpful to the client. Like I said, we can't know all the details, so everyone is just trying to help as best they can.