I should have posted that I do wash (er, rinse) my bottles. I triple rinse them as soon as they are done and hang them on a bottle tree to dry. Then sanitize them of course prior to filling. I do not however, wash them out (on the inside) with oxy or any other cleaner so maybe thats why? I do rinse them really well though (I feel). They say the beer taste is very light and not bad, just noticeable, and not in every bottle. So maybe it is the rinse. I thought I may have some transfer from the auto siphon as it is plastic and the tubing vinyl.