I am not an expert, but I have replaced our TPO membrane myself, along with a fair amount of damaged luan plywood. Those memories are not fond ones...
All I can tell you is how I'd think about it if I were in your shoes.
1. Yes, I'd want to be sure everything was thoroughly dried out.
2. Is there someplace you can get it indoors temporarily? I replaced my roof during the first part of a November. I rented a heated storage unit that the rig would fit in...
3. If I couldn't get it indoors, I'd be tempted to try to "hold my ground" by protecting it for the remainder of winter until things warmed up (or at least I had a stretch of good weather coming).
4. To be sure everything dried out, I'd probably think of cleanly cutting a flap in the TPO that would hopefully encompass the potentially damaged area.
5. Once dry, see how the plywood is. I can tell you that luan ply and water really don't go well together.... (sorry).
6. After any plywood repairs are done, perhaps re-seal the flap with Eternabond tape.
7. A word about TPO. The older TPO has a felt-like backing that tends to wick water (fantastic idea, right?). New stuff does not...
Just my initial thoughts. Good luck!