Sometimes when I buy milk, whether it be regular supermarket milk, some local grassfed variety, or a pricey organic one, sometimes there is a taste to the milk, an aftertaste that reminds me of petroleum jelly. This is something I've noticed in drinking milk since I was young. What could be the cause of this? Age of the milk? Diet of the cow? I remember buying Trickling Springs through the winter months and it tasted exactly of this the entire winter.