This has happened to me as well, to ruminate more about the session when I had days off after. But when I did't have days off, I would get really anxious at work thinking about it.
I think attachment to the T might cause maybe issues because there can be a lot of expectations around being there, maybe you on some level want to be more open or feel more closeness. You said the session wasn't too deep or intense - maybe you had the need to actually go deeper into some issues and when it's not happening, your unexplored feelings stay with you and you start ruminating.
Of course I cannot know how this is in your case but I'm going through something similar.
I'm lately always getting sad when when I see there are only a few minutes left out of the session - which sucks, I don't like it at all.
Maybe talking to the T about all these could help..