I have had Nics in the past, and I think just like any Boa, their temperament ranges from individual to individual. Some do get the classic Nic attitude, some don't, some get it earlier in their life some later.
However, I have noticed that almost all of my Boas, as they get older or reach a certain adult age, have to start being removed from their cages by hooks. Once out, they are completely fine. Maybe it's just because as they get older, their sense of territory gets stronger, and are territorial of their cage. Maybe its just the simple fact that they are bigger, and you never really noticed that defensiveness in that tiny little boa, cuz well, it just didn't really matter. LoL. Hope this helps.