I've been ageing a bottle of Sierra Nevada's Torpedo Extra IPA (7.2%), bottled in mid September 2015. It has developed about an inch of sediment that looks like yeast. Anyway, I'm dying to try it to prove that old IPAs are the best (eh?), but I suspect the sediment is some sort of protein. I've noticed it in other (non-bottle conditioned) beers such as Lees Harvest Ale 2008 and Scaldis Noel (BB 2008). Does anyone know what is happening to the beer?