I noticed my xenia is looking a bit shriveled too. The only thing I've done out of the usual recently is feed them bbs, that wouldn't do anything. And I dosed the tank with some magnesium chloride. About 8 teaspoons. Brought the magnesium up from if I remember right 1260-1280(holy crap, do I need 50 teaspoons to get it up to 1350?) I wouldn't think that slight of an increase in magnesium would upset the brain or the xenia? And the chloride from what I'm reading would have gone up about 40ppm, but the normal amount in seawater is about 19,000 ppm so that's practically no increase too.
It's probably just a coincidence that the xenia is grumpy now.