And look! It has grown wings! It must be close to maturing.
Young dragons are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it marks the beginning of maturation. At this point they are often capable of hunting on their own and are usually left alone by their mother.
Tibbit seems to be the youngest of the hatchlings, and arguably the cutest. The older girls tend to take turns watching out for her, as he naive and curious nature can sometimes get her in trouble. None of them seem to be able to hold a grudge against the cheerful and childlike hatchling, however. As for being frozen, it's debatable if Tibbit had ever considered adulthood as a natural consequence and seems quite content at the age she is, seeing the world through a child's eyes.