I was finishing up a rowboat ride with some friends, and I had occasion to ask "Is that your hat?"

This brought to mind a song I heard once, "The Long, Tall Texan." The version I remember differs some from what I find on the Net. The last verse goes:

Oh, I'm a long, tall Texan, and I enforce the law.
(He rides through Texas to enforce the law.)
repeat
People tum-tee-tee and they say to me
"Hoo-ray, hoo-rah, are y'all the law?"

My question is, is this use of y'all to refer to one person authentic? I have seen plural forms (ye, Sie) indicate formal address at times. Is that what's going on here, or did the composer just find it more fun to sing "y'all"?