It's not normal and I suspect you may be seeing an animal with a viral infection . I would get it as far away from Taz as I possibly could especially since this came from a pet shop (exposed to may other different animals that are imported and could possibly be be very ill )
Make an appointment with a vet ASAP as you do not want this speading most viruses that cause this type head movements are not cureable and spread rampantly . In all of the years I have been keeping tegus I have never seen this in a tegu but I don't mess with any imports and I don't bring in any new tegus .
I've seen viral infections whipe out entire colonies of bearded dragons , monitors , and boas where sick animals displayed this "stargazing " head movements .
At best the animal was just physically injured and has neurological type damage but I would not chance it . If I saw this in any animal that was near my tegu collection I would be freaking out .
Quarentine all new animals especially if they come from a source that handles any kind of imports. If they are showing any signs of being sick or ill it is not worth the chancing bringing them into a collection . Rescues like this can quickly go sour and are best left to the care of people who are set up to specifically to handle them (on staff vets , proper quarentine facilities etc. )
Stella St.Pierre
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Stella St.Pierre
www.bluetegu.com