Good point del. I'll chime in with the little I've read up on snakes and motor control issues.

I've seen a few individuals of various species of snakes reported to have motor control issues, including ball pythons that weren't spiders. The BP I can recall seeing a vid of was not the offspring of a spider.

The other snake species were not offspring of BP spiders.. obviously. Some were "normals". Some were morphs. In particular, the "jaguar" carpet python morph has "neuro" issues associated with it.

Much like there are many issues that might cause motor control issues in humans (parkinsons, huntingtons, MS, Tourettes, MND, and I'm sure there are more), I'm sure that there certainly are a variety of causes of motor control issues in snakes.