Actually the scriptures may have been changed. The instances of Lord could have originally been the tetragrammaton. It was later changed to Lord or PIPI in greek. Here is a paragraph explaining. YHWH in the New Testament
"Girolamo, the translator of the Latin Vulgate confirms this fact. In the prologue of the books of Samuel and Kings he wrote: "In certain Greek volumes we still find the Tetragrammaton of God's name expressed in ancient characters". And in a letter written in Rome in the year 384 it says: "God's name is made up of four letters; it was thought ineffable, and it is written with these letters: iod, he, vau, he (YHWH). But some have not been able to decipher it because of the resemblance of the Greek letters and when they found it in Greek books they usually read it PIPI (pipi)". S. Girolamo, Le Lettere, Rome, 1961, vol.1, pp.237, 238; compare J.P.Migne, Patrologia Latina, vol.22, coll.429, 430.
Around 245 C.E., the noted scholar Origen produced his Hexapla, a six-column reproduction of the inspired Hebrew Scriptures: (1) in their original Hebrew and Aramaic, accompanied by (2) a transliteration into Greek, and by the Greek versions of (3) Aquila, (4) Symmachus, (5) the Septuagint, and (6) Theodotion. On the evidence of the fragmentary copies now known, Professor W. G. Waddell says: "In Origen's Hexapla . . . the Greek versions of Aquila, Symmachus, and LXX all represented JHWH by PIPI; in the second column of the Hexapla the Tetragrammaton was written in Hebrew characters." - The Journal of Theological Studies, Oxford, Vol. XLV, 1944, pp. 158, 159. Others believe the original text of Origen's Hexapla used Hebrew characters for the Tetragrammaton in all its columns. Origen himself stated that "in the most accurate manuscripts THE NAME occurs in Hebrew characters, yet not in today's Hebrew [characters], but in the most ancient ones". A biblical magazine declare: "In pre-Christian Greek [manuscripts] of the OT, the divine name was not rendered by 'kyrios' as has often been thought. Usually the Tetragram was written out in Aramaic or in paleo-Hebrew letters. . . . At a later time, surrogates such as 'theos' [God] and 'kyrios' replaced the Tetragram . . . There is good reason to believe that a similar pattern evolved in the NT, i.e. the divine name was originally written in the NT quotations of and allusions to the OT, but in the course of time it was replaced by surrogates". - New Testament Abstracts, March 1977, p. 306."
The article is an interesting read if you are curious.