But the writers of the Gospels, I believe, were educated types who would have been exposed to the Greek culture
Was Isiah a gospel writer ? The common perception was that the earth was flat. Any proof that Isiah would have been in contact with Greek astronomers or is this just assumption. I'd rather go with Brian's theory, although it still comes across as speculation of what MUST have happened.
Either way, with exception to Paul, I don't see any of the Gospel writers as particularly educated.