They only usually curl their tails up tightly when they are sleeping. When Lily used to come out she would hold her tail right up straight like a cat's tail while she was walking along! As she can use it for other things, I would think that it's ok. Sometimes they do just sit with the end curled a bit.
Well when she just lounging around she wraps it round the branches and leaves but I have never seen her with a tight curled tail. Maybe she does on a night when everyone sleep just I never saw her do it and I wondered if it was normal or would she do it more when she gets older!!
Yeah i known chameleons curl up their tail the same way humans would curl into a ball when sleeping, if you are feeling somewaht unsafe. You dont want your far-reaching limbs exposed to.. anything.
Just a natural behavior they have in the wild, instinct now
Just because you haven't seen her do it, doesn't mean she doesn't! They are good at hiding after all. As long as she's still using it (like you said, wrapping it around vines and using it for movement), you have nothing to worry about! Try and spot her after her lights have been out for a while and she's definitely asleep. It'll normally be curled then, but, if she's anything like my guy, she'll be impossible to spot!