October is the time many Argentine tegus are going down for hibernation. They go off-feed, spend more time hidden, and eventually hide completely for the winter. Babies to adults will do this. Bert's tegus are kept outdoors so the parents hibernated every year.
I had an Arg B&W many years ago that was Agama stock. A really robust tegu. But he went down completely for hibernation (filling up the access hole in his hidebox with mulch) and remained there, sight unseen, until May. Yes, that's correct. From November until May I never saw him. I knew he wasn't dead because I didn't smell anything bad.
I did not disturb him physically, but the cage remained at warm temperatures (like those you are using) all the time he was down, so temperature had nothing to do with his decision to hibernate. Nor did lighting -- the cage was getting 12 hours of light each day. Tegus know what they're doing. They can sense seasonal changes and it's really annoying when people don't understand that and keep digging them up while they're trying to hibernate (they don't eat while they hibernate and their metabolism slows way down). Anyway, when he finally emerged in May he drank like there was no tomorrow. Then he started eating and growing like nothing I've ever seen before. Really amazing!
Just give Bert a call if you're concerned, but expect him to go off-feed. Keep offering food, though. Let him make the decision. Know that if your tegu wants to hibernate he is going to hibernate, whether you agree with his decision or not.
As for taming, babies are skittish and many do not like being handled. But as they grow and you continue to interact with them they will usually calm down and trust you. Be patient.
Bill