Hm.

Maybe he does "emotionally turn off the light" with his other clients too, but you don't notice it because you didn't see what he was like with them 5 minutes before?

Or maybe you saw him with another person after a session that wasn't very emotional - maybe he feels the need to disconnect only after really intensely emotional sessions?

It kind of makes sense that if you are dealing with something really powerful, he will need to disengage at the end of your session if he has another client coming in - he needs to be ready to give them the same level of attention he gave you, and it wouldn't be fair to them if he was still wrapped up in your problems at the beginning of their session, just like it wouldn't be fair to you if he was still wrapped up in the previous client's problems at the beginning of your session.

I don't know - those are just my speculations.