I feel like the pianist trained you rather than you achieving it like a little kid does. That happens sometimes if you put in the effort (learning/memorizing/training). While I am not old enough to know how it changes, could it be perhaps that what you had learned when you were 16 was in your mind a certain pitch and as ears change (a 16 year old can hear higher pitch than 30 year old), you don’t relearn it, therefore it’s shifted? Please correct me (pretty sure I’m wrong)