Even after sketching and working some time on a drawing we may be oblivious to some mistakes from the very start. Even after the picture is complete, one may be so invested in it that, for all purposes, the picture looks perfect. I, at least, have the habit of thinking " ... nah, it looks great", until I look at it a couple days later. Sometimes it's even hard to pinpoint the exact location/way that said picture looks wrong, but it's far from the perfect state I once thought. I imposed the habit of trying to look at the pictures from an outside point of view, but even so, it may be hard to figure out what's wrong, and depending on the phase in I'm in, I may not bother changing it, since, as it was said, the entire picture as a whole looks good.
I would say that the picture presented here looks really good, as a whole and at first glance, but if one was to get technical, the said arm irregularities are clear. I'm aware the product is finished at this time, but even if it weren't, the picture was at such an advanced state that I would advise against making said changes. It may be beneficial to post in a sketch next time witch would make posterior changes much more easy :3
One more "piece of advise"
In order to grow as an artist, you should always be critical. It's true that the arms don't damage the picture so much, but if you're ok with it, there's nothing stopping you from making the same mistake again. You should always criticize your work as much as you can without starting to hate what you did. NEVER hate anything you do, even if I don't like a finished piece that much, if I learned something from it, I consider it a huge success.
Anyway, that's just my take on the whole subject :3