Is it ok to put a vial/pack of yeast back in the fridge? I want my starter to be ready to pitch at high kraesen, but if i pitch now, it’ll probably be past by tomorrow afternoon when my brew will be ready. Will leaving the pack at room temp for the night stress the yeast?
You’d be better off to refrigerate it.
I am assuming it was not out of the fridge for THAT long. So yes, put it back in the fridge until you are ready to make your starter.