Alkalis in the surface of the inside of the bottle can be leached by the alcohol, raising the pH enough that it actually attacks the glass. To avoid this most g

Alkalis in the surface of the inside of the bottle can be leached by the alcohol, raising the pH enough that it actually attacks the glass. To avoid this most glass bottles are dealkalized before filling, but if water from a humid environment makes it into the bottle before filling it begins a process which leaches various compounds from the glass. But this would take a long time to occur in whiskey (vs Vodka/Gin, which are less acidic). Oxidation is probably more affected by the sealing method than anything else. Corks also change the flavor of whiskey due to things like absorbing certain compounds depending on what they are made of or coated with.