That's exactly what my pastel does....not often, but every now and then, he spins backwards, just slightly, just enough so you look and go wth?? He also stops when distracted. I didn't notice it until he got to be about 300g, although it may be that I just wasn't around for it before then. It's not severe, it's barely noticeable, but it looks like what I have seen actualy spiders to in videos, to a lesser degree. It doesn't bother me, but it could be a trait that is dominant with the spider gene, and maybe carried as a recessive in a spider cross?