The Oddity of the End of the Letter

Dr. Prothro: Paul's in prison, but the Philippians have sent him a gift. Epaphroditus is the sky from Philippi; he's come to Paul when he's in prison there and brought him a gift of funds. Dr. Prothro says it feels kind of like strangely tacked on at the end. But St. Paul here is kind of coming back around to reflect with the Philippians on something that is, in many ways, kind of the occasion for the letter?