I’d suggest bringing the bottle in out of the cold and setting it down so it rests stably a bit off plumb. It’s possible some moisture got into the bottle after it was opened, and condensed/froze in the cold. With the bottle a bit off plumb, the low point would be along the bottom edge, so if there was enough moisture to form a droplet, it would sink to the low point and you might be able to see it.
OTOH, it’s possible that the stuff simply turns cloudy in cold temps, in which case it would clear up as soon as it warmed up.
Hmm, something to test next cold snap