Saison Rue Dregs

As I have been unable to brew for a while, I have been using other outlets for my brewing itch. One such outlet has been collecting a bunch of dregs from beers.
I have been storing them in 100ml sterile plastic cups.

Anyways. Everytime I checked in the Saison Rue dregs, the cup was definitely expanded from gas. After opening and closing it several times I decided to leave the cap loose for a bit. Mind you this is in the fridge. Just checked on it, and well, it is fermenting... There is a small pellicle starting to form in the top.

Can Brett ferment at such cold temps?

That was a long ass buildup to a simple question.

I am not sure if brett can ferment in those temps but i have had beers that got some brett and refrigerating it helped but it still kept fermenting so from experience I wsould say yes.

It's possible it is something else besides brett too, other infections can cause a pellicle too.