I had finished up my brew about a month ago and bottled everything up. I was away for about 3 weeks for work, came back and had a beer. It tasted fine, nothing was growing in it or anything. I was away for work for another 10 days and just returned. i looked at the top of my beer bottles and saw these things forming in almost every bottle. my question is, "is this a yeast raft somehow forming 4 weeks after being bottled? or some infection that is rearing its ugly head just now 4 weeks after bottling?" I have read many threads about yeast rafts but havent found any pertaining to them forming well after bottling so any advice would be greatly appreciated. Thanks All.