My yucca plant appears to have entwined and knotted the middle 6 or 8 leaves in a cone shape as though to shelter the middle of the plant. The plant is about 15 years old and I have never seen this before. Is this something I should be concerned about.
It sounds as though the center leaves are not unfolding as they should. This can because by a few environmental factors. Most of the time, it resolves itself, but you can spray the plant down with a hose and that will help the plant get extra humidity which will help with the leaves unfolding. As long as the plant looks otherwise healthy, I would not worry about it.