@skinnylatte my first question would be "does the effect survive a double-blind trial?" :blobfoxlaughsweat:
but otherwise the mineral content others mention could be responsible? I'm very skeptical of the proposed aeration mechanism since it's being poured over anyway.
I used to microwave water for french press coffee before I got a kettle and I've never noticed a difference, so that's part of what informs my intuition for a psychological effect here