Upload & Sell: Off
The focus in on her arm, yes. Honestly, though, I have seen so much worse in big prints that people passed off (and not had anyone notice). Have you already done work on the face to get it sharper?
(and just a small personal crit...I find the in-focus tree branch/trunk on the left side of the frame to be rather distracting...might want to see if that bothers you and consider blurring it a bit.
I'd soften the branch/bark on the left of the image as it's bringing attention away from the subject (due to her not being in focus perfectly). But fix that and I think it'll be good to go. As Joel says, I've seen far worse. The light and composition is good, and if they've selected it as the largest print they clearly like it as well, so I think you're good to go :-)