I have two batches of beer (well, the remnants, less than two sixes of each) made early this year, both well-hopped pale ale styles, both made sequentially, the second made on the yeast cake of the first. Until recently, I would say that both batches had a nice head, good lacing. Then, within the last month, they have -both- started to foam up and out of the glass, no matter how much I chill or how carefully I pour. A regular 12 oz. longneck will produce foam that will come up out of an Imperial pint glass. This is a thick foam that can practically be cut with a knife. Beer still tastes OK, and I'm certain that the cleanliness of my glassware is not an issue here. I prime with 5 oz. dextrose (corn sugar), and out of maybe 60 batches of beer made in the two years I've been brewing, and a wide variety of styles, this has never happened. Any thoughts, ideas speculations?