I've had a common problem lately with a number of my batches of beer. Before I open the bottle (750 ml glass), everything looks good and the beer is nice and clear. I'll pour a glass and everything is good. However, in the remaining beer in the bottle, all the yeast comes up off the bottom and resuspends and the beer foams up and starts overflowing out of the bottle. It's not a gusher and the beer tastes good and everything (e.g. no infection). I've had this happen in several batches now and it's not consistant; a bottle from a batch may not do this and then the next one will. Has anyone had this happen or know what's going on?