It is strange, but not unheard of. The wobble in spiders is a neurological disorder. It's possible to have a non-spider animal exhibit the same behaviours. Sometimes a spike in temperature during incubation can be the cause of this, and it's likely permanent. Sorry, goodluck

P.S. There is always the concern that of IBD but if you've had it for a while and it's been like that since it hatched, so IBD doesn't fit the bill.