Brewed a cream ale and it turned out fantastic. Kegged it into a corny keg that was filled with star san which was forced out with co2 and spunding valve. Closed transfer from all rounder using co2. Beer came out a little undercarbed after a week but tasted and looked fantastic. Upped the co2 for another 3 days. Beer was amazing until 2 days after that. Noticed it got a tad bit darker and has an off flavor. Almost like an artificial plastic taste. Don't think it's bandaid plastic but all the same.... using new eva barrier lines and the keg hasn't been exposed to oxygen as far as I know. Seems kind of quick to be oxidation. Carbonic acid maybe??? Thoughts?