I made a Ferocious IPA kit last month and when I initially tasted it, a few days in the bottle, it was pretty great. It could have been a bit more balanced, so I set 12 or so aside to see if the hop flavor would blend a bit more. Last night, after it had been sitting another week and a half or so (six weeks since bottling) it has a cidery flavor to it, and the hop bitterness has been replaced by a tart unpleasant bitterness. Is this what happens to IPA's over time? I've read they degrade. Or is it a process thing? Infection? I have another batch fermenting and would like to avoid this happening again if possible.