In reference to a fellow Christian being referred to as 'brother' as in the teaching in the first half from Paul's letter to the Romans. I also cringe when I hear someone refer to someone else as 'brother' when it is in the first person. I'm nit picking, but Paul does it here in Philemon. I just had to throw that in for interest sake.
Philemon Authorized (King James) Version (AKJV)
1 Paul, a prisoner of Jesus Christ, and Timothy our brother, unto Philemon our dearly beloved, and fellowlabourer, 2 and to our beloved Apphia, and Archippus our fellowsoldier, and to the church in thy house: 3 Grace to you, and peace, from God our Father and the Lord Jesus Christ.
4 I thank my God, making mention of thee always in my prayers, 5 hearing of thy love and faith, which thou hast toward the Lord Jesus, and toward all saints; 6 that the communication of thy faith may become effectual by the acknowledging of every good thing which is in you in Christ Jesus. 7 For we have great joy and consolation in thy love, because the bowels of the saints are refreshed by thee, brother.
Because Paul did it here in writing, I do wonder if he ever did it verbally when he was with fellow believers.