Period 1960-1967 was probably the best period for Greek society and thus Greek music.
Mainly the first 5 years of the decade a new wave of composers were responsible for high productivity in records companies.
On 1964 Theodorakis released Elitis' "Axion Esti" and on 1966 Ritsos' "Romiosini", works which seem like the "Parthenon" of Greek music culture.
So yes, what you're talking about is a coincidence.
"Gilgamesh, where are you hurrying to?
You will never find that life for which you are looking.
When the gods created man they allotted to him death,
but life they retained in their own keeping"