A good wine improves as it is exposed to oxygen in the glass after it is poured.
Since one is supposed to say a Berachah of HaTov VeHaMetiv if one drinks a better glass of wine than the first (ie., first of that meal, the one over which one recited HaGafen), does that mean that, if the same glass of wine noticeably improves after a few minutes of air, one should make this Berachah? What if it improves in the bottle or decanter between drinks?
Since the glass or bottle of wine is on the table when the original beracha of "borei pri ha'gafen" was made, I don't see why one should consider making "hatov ve'ha'maytiv."
On a secondary note, I seriously doubt that anyone can notice a marked improvement in a glass of wine afte five minutes unless they talk themselves into it. I used to sell wine and experts tell me that leaving wine to breathe does very little to change the quality. They have measured the oxygen in the wine when first uncorked and after specific intervals and found insignificant chages in the levels.
