I brewed a beer, bottled it. The first three weeks it was great. Last week, I noticed just a hint of phenolic / bandaid / rubbery smell in beer as it warmed slightly. Tonight it was very noticable. Not overpowering, but very present.
At first I considered it to be a yeast flavor. I used a phenolic saison strain, WLP566. Normal fermentation temps, nothing hot. Maybe 72F at the warmest. No unusual things about fermentation. No off flavors at any point prior to last week.
We do have chloramines in our water. I have been using an activated charcoal filter to filter my brewing water, but otherwise no additional pre-mash treatments to it.
This only shows up after bottling, and only after a few weeks. I am thinking it is either water related or wild yeast. I don't use any chlorinated cleaners, but from time to time do sanitize at normal levels with betadine. Mostly star san.
What would cause an off flavor to appear this long after bottling?
For bottling, I typically use a cup or two of charcoal filtered water, some table sugar, boil for about 5 minutes then pour still warm into the bottling bucket and stir to incorporate into solution.
The bottles I sterilize in an oven at 340f for about an hour and a half.
I have made quite a few beers but only noticed this one two of them. Other beers never had an obvious phenolic off flavor. The first time it happened, I think it was an infected starter for some lacto I pitched.