I read a comment on /r/homebrewing today saying that it's advisable to use a tube to drain pre-boil wort to a kettle to minimize oxidation. My understanding is that oxidation is not a concern pre-fermentation, but the user asserted that it is, indeed a concern for pre-boil wort (but is ok and recommended post-boil and pre-fermentation, which I already knew). Can someone confirm this either way?