Hmmm.. I know about the 'Angel's Share' - but that's when the whisky is in the barrel and it slowly evaporates over time. Although I didn't think it should not evaporate once bottled - but that is assuming it's properly sealed. After 30 years, it makes you wonder if the seal is still as good secure as it was all those years ago??
Doesn't hurt to contact JD - let me know what they say!
And hey, what are you waiting for? Sounds like time for a party!!!