Knitter's Lament

I spent six hours this morning flying from Boston to San Francisco to visit my son and his family. One of the things I brought with me to pass the time was the shrug that I am knitting. It's an interesting pattern which is knitted in two parts: each starting with the sleeve and working toward the center back which will be seamed together and the front which is held together with a brooch. The left side is finished. The right side is in progress and almost done. Wait! Something's not right. Why does the shaping seem vaguely familiar? You guessed it..... I made two left sides! Just not following directions. I'm not as pissed as I thought I would be. I'm reading "The Yarn Harlot" and I'm learning that I'm not unique. Even the most experienced knitters make mistakes. So I'm back to frogging half of the second piece.