This week I went to a couple of fairly nice restaurants in Denver. At the first one, I had a draft Stone IPA. As I sat and sipped and the beer warmed, I began to notice.... That distinctive band-aid flavor that indicates phenols. With a sigh, I finished the beer. Then the next night I had a draft Negra Modelo at a different recipe. The first off-note I noticed was green apple - nothing the restaurant could do about that. Then, again, I began to notice band-aid. Two restaurants, two consecutive nights, two off-flavored beers. Given the quality controls these two breweries likely use, I rather doubt either was fermented too warm or used over-chlorinated water. My hypothesis is dirty tap lines. Okay, guys, what do you think could have caused the off-flavor in the professionally brewed beers?