Remember, the top of the AI/TI masts are meant to rotate. I tape my mast pieces with duct tape, but no longer worry about the sail twist as it always seems to work itself out.
why are they meant to rotate? that would seem to defeat the purpose of the roller furling.
i have my mast taped and my downhaul is installed. still spins. when i return from a trip, i frequently find that the downhaul needs to be moved 180 degrees to alleviate the twist in the sail.
i also have issues getting the last half turn out of bottom of the sail because the top is already fully pulled out
the only reasons i can see for having a two piece mast are; cheaper shipping and it is difficult to manufacture long carbonfiber poles.
Tolerances look pretty tight on these masts. But you might want to check if there's a flaw that's resulting in some unusual looseness. If it keeps on rotating on you despite doing what everyone else is doing, you might want to have your dealer look at it and compare it to other masts in stock.
i will check my tolerances and see if it's very sloppy.