Yes, cold worn fluid will do this.
I would try changing it, using the 4 quart drop method, and see what happens. If you have taken really good care of your tranny in the past and had a flush or two done to it, then I would say that it was ok to do that. But if not or you are unsure of the history of care, then just do the 4 quart change by pulling the drain plug on the bottom of hte tranny and refilling.
