Finished Socks

I can hardly believe it. I finished these socks last night,
then washed and dried them early this morning. Here is something interesting about these socks. The first one I made, (the one with the orange ribbing) I made in the regular way with both yarns in my right hand. The sock with the yellow ribbing. I made holding the yellow yarn in my left hand. The "orange" sock looked smooth and the yellow one bumpy! Is that just because I am not all that adept at holding the yarn in my left hand? Washed, the difference is not too pronounced. I think I read something about this somewhere, but where? Maybe you can tell me and save me the effort of going through a zillion knitting books and articles!