I kegged an IPA and the first two days it tasted great. Then, it started tasting astringent I think. I can describe it as a lingering bitter aftertaste and almost dry. I know IPA's are suppose to be bitter, but this is just different. What really has me stumped is that it tasted great the first two days and now it's not good. I dry hopped with Columbus and the aroma is considerably down than before. Any suggestions as to what happened?