Hmmm, just the one plant?
And the rest of the plants are still long and white of pistil?
And you haven't treated her any differently?
No kine spray?
Hmm.

Take a close look at the new growth.
Look a li'l "bunchy" or twisted?
I'd grab a 100x 'scope and go hunting for broad mites.
Easiest way is to lay a slice of potato on the surface next to the stalk.
They can't resist it. Let them come to you.
Wait a day, then 'scope the potato.

That said, I did once have a plant that pulled in it's pistils early.
They all browned and shriveled up at the same time too, top to toe.
Left the itty bitty buds looking oddly roundish, kinda like marbles.

Didn't have a decent microscope at the time.
Looked like super, sudden, senescence!

Never did figure out what caused it.

Please let us know what you find.
Aloha,
Weezard