I think asking for a light session is a good idea. I've done that before (so has my T when he felt like I just needed a session to kind of center myself).

I had a couple of sessions were I went into full hyperventilation mode that T had to physically help me out of. I used to have very strong physical reactions due to flahbacks and dissociation. Not fun, but fortunately very temporary and survivable.

Our lighter sessions were nice and even productive in a different way. Ask for what you need.