All wines contain some acetic acid, and novice wine drinkers often confuse this with the normal acidity in dry wines. Too much acetic acid causes a creeping sensation on the roof of the mouth, front to back. Give the wine a sniff test, too. It probably smells like nail polish. Often confused with bitterness, astringency is a result of a wine's contact with grape skins, seeds and stems.
Wood used in barrel-aging also contributes.
Look for this on the very back of the tongue. It's the last of the four basic tastes to evolve when something is eaten or drunk. The mouth and tongue perceives this as a warm feeling in the back of the throat. If an apple is sliced, then left sitting on the counter for a while, it will brown and the flavor will start to change, a result of the apple's exposure to the air. The same thing happens to wine.