While confirming the importance of Greek, it is not exactly surprising. I mean, Greek was the language of science and literature, and was the common language that permeated the area from 300 BC to 600 AD. It is not exactly unexpected that any Old Testament coppies from after 300 BC would be written in Greek.
I find it unexpected, because I thought that the Jewish communities always kept the scriptures in Hebrew, regardless of what language they spoke in daily life.