I've written on Augustine and the Septuagint elsewhere, but I've recently come across this quote which is interesting:
"But, if scribal error is not involved, it must be believed that, where the sense corresponds to the truth and proclaims the truth, they [i.e., the seventy translators], moved by the divine Spirit, wished to deviate [from the Hebrew text], not in the manner of interpreters [i.e., translators], but in the freedom of those prophesying. Consequently, the apostles, in their authority, when they appealed to the Scriptures, quite rightly utilized not only the Hebrew, but also their own - the witness of the Seventy" (Augustine, City of God, 15.14).
