Suggestion: Consult with your brew shop when in doubt. My experience is they love helping and they are a quick phone call away. Better than ruining a batch of nips, or worse, 5 gallons of beer and hours of your time.
My vodka was in the freezer, so I covered my nib-vodka concaction with some plastic wrap (in a glass measuring cup) and microwaved for about 40 seconds: a little warmer than room temp.