To Breath or Not To Breath, that is the question

[BojoLay]

Before enjoying a bottle of dark red wine like a Cabarnet or Melot should one pop the cork and "let it breath" a spell (20min) before consuming? Or is that just old none sense?

A couple of Sundays ago I drank a bottle of Windsor vinyards Cabarnet Sav. (a gift with both mine and my wife's name on the bottle) while having drinner. The first glass was sort of harsh or acidy. The remainder of the bottle went down very smooth and quite flavorful. Is that because it had time to breath? Or did the first glass numb my taste buds?