I brewed a batch of bitter 5 weeks ago, simple recipe with 90 % pale malt and 10 % crystal. IBU is aout 30. I have brewed this beer before, and it was great.
Everything went perfect, up until I pitched yeast. It is a long story: re-pitched yeast harvested from primary from earlier batch (WLP002), but I pitched way too little. The fermentation did not start within 48 hours, so I repitched fresh yeast. That is to say, the wort was aerated 48 hours before the "real yeast" was pitched.
The fermentation then proceeded as normal.
4 weeks later, properly carbonated and all, the beer tastes bad, or "not that great". Definitely not infected. It is a strong yeasty taste (the beer is clear), with sawdust like notes, and the bitterness is very pronounced. All notes from caramel malt etc are gone. But to call it "wet cardboard" is a stretch, but then again, I have never tasted that.
Is my beer oxidized?
Edit: I have noticed that the bottles have all small bubbles on the inside of the glass. Some bottles have a very, very thin film of something oily in the air/beer interface. Could it be a beginning infection?