I would be more concerned than your vet seems to be. Keep a very close eye on her and if the wobbling seems to get worse, or if she becomes lethargic, be prepared to take her in right away.
IMO it's highly unlikely that this was caused by the dewormer. The worst I've seen a dewromer cause was a bit of runny stool. I'd think it was the rabies vaccine that caused it, and because of that I'd be very cautious about giving her that vaccine again. It has been my experience, with pest as well as people, that if they have a mildly poor reaction once they are much more likely to have a severe reaction to that vaccine later on.
In any case I wouldn't worry about the dewormer, my cats get it about once a year or so. I do feed them raw, but even an indoor only cat can get worms from bugs they catch in the home, other pets, or even your shoes. Better safe than sorry.