Roger, probably because they were grown a few miles from where you were eating them instead of being picked, cleaned, chilled and transported across most of Europe.
I'd add, why does retsina taste great in a taverna in Greece, but instantly turn into turpentine if you fly it back home?
Probably the state of mind of the recipient has a lot to do with it, your on holiday, no stress, relaxed, a few beers in your tummy.
Damn........ I need a real hollerday again.