Episkopos and Diakonos

The article on Philippians (written by Gerald Hawthorne) in IVP’s Dictionary of Paul and His Letters says this:

The terms “overseers” and “deacons” (1:1) occur here for the one and only time in Paul’s letters, but without any elaboration on what these people did or about what kind of authority they exercised within the church.

Unless I’m missing something, this is demonstrably false. “Overseer” is rendering the Greek episkopos, which also occurs in 1 Timothy 3:2 and Titus 1:7.  “Deacon” is rendering the Greek diakonos, which occurs frequently throughout Paul’s letters. Admittedly, Paul normally uses diakonos in a non-official sense, but he does sometimes use it to refer to the office of deacon (1 Tim. 3:8, 12). So what gives?

Does Hawthorne mean that this is the only time the terms occur in Paul’s ecclesial letters (i.e. his letters written to churches)? That would have been an easy thing to communicate. Does he assume that Paul didn’t write the pastoral epistles? That would be lame. Is Hawthorne working from an English translation that renders episkopos as “overseer” in Philippians 1:1 but as “bishop” elsewhere, and is that what he means? That wouldn’t seem in line with the scholarly standards of the dictionary as a whole. Does he mean that this is the only time in Paul’s letters that the two terms appear side by side? That may be true, but seems like an insignificant thing to note. Does Hawthorne mean that this is the only time the terms appear in the plural? That may be true (at least in the case of episkopos), but again seems like an insignificant thing to note.