Two of mine(Sansevieria elliptica horwoodi FKH424 & S. fischeri) both had folded leaves, too. Earlier this summer the weather was cool with lower night temps than normal, so I cut back on watering and the leaves folded. I think they were protesting both things. Since increasing the amount of water plus the temperature is warmer the leaves have unfolded and returned to near normal.

As you are in California and zone 10 I'm wondering if your plants may need increased watering at this time of year. Maybe once a week is not sufficient right now.

I'm a novice grower of these but really love the sans and being in Ohio it is hard to balance between temperatures and watering so my advice is given with a grain of salt(maybe several grains) particularly due to my inexperience. lol. I know I lost several last winter and was truly heartbroken, so my suggestions may not be the best. - Elaine

Thanks Elaine. That is the same advise I got on another forum, so you must have more knowledge than you give yourself credit for. :-)
I am going to up the water to twice a week now on those with folded leaves. Will report the results.
We have been having some strange weather for S. Calif. It has been rather hot during the day (but not like what is typical for August,) but it has been kinda cool at night. Still around 60 though so I am not worried yet about bringing them in. I will be soon tho. Starting to wonder where I am going to put them all. At least they don't have to go right in the windowsills like the other plants, & I can place them around in somewhat less light places. Love the sans because of that for sure.
Marcy

Yes, please post your results regarding the increased watering. It is the cooler nights that always concern me, too.

We have also had an unusual summer with lots of rain and very cool nights. Several have been down in the 40s and I have my sans on an enclosed porch so they been okay so far, but the temperature still gets pretty cool there overnight when it drops that low.
I'm hoping for a warm indian summer so they can be kept out a little longer. They love the warmth. I hope yours respond well to the increased watering. - Elaine

Also, do a search here for this same subject. There was discussion of this earlier this year, and mine is still doing the 'taco' thing even though I have increased water, and sun. Found out lately I'm not 10, but Sunset 24...

I have only the one doing this. And it hasn't grown in a year either! Maybe food would help.

Cena...what is the difference (climatically) between Sunset 24 and Zone 10? Wondering now what Long Beach is?
Marcy

Me too . . I'm in Sunset 22 (close to 24). Its been a cool summer here too and all my parvas have folded their wings, but the trifasciata only slightly. All my plants are in the open, but it doesn't seem to make any difference whether the parvas are in mostly shade or mostly sun. I've been watering twice a week with water that has a little Miracle Grow in it. My soil is gravel and pumice, so it drains fast, but its hard to tell how fast it dries where the roots are. All the plants seem to be growing well and look healthy - at least to my eyes.

Marcy, I haven't a clue. I was 'told' by a customer that where I live is Sunset 24. I suspect much has to do with coastal or inland, micro or other climate. Who knows? This was an experienced grower of roses in my own community. Hard to argue or find a knot ot cling too when knowledgeable folks storm the walls...

My plants look healthy also. I have No Idea why this behavior occurs. Most frustrating. I sure hope someone tracks down a faint clue or idea. I would embrace (almost) dancing naked on/during a full moon to prevent or reverse this odd behavior. If the weather was warm, it might not even take a long talking to...

LOL ......Cena you're a riot. It would have to be a much bigger problem to get me to do that. Ha Ha (Maybe making all mealie bugs and aphids go extinct or something might do it..ha ha)

Wanted to give an update to this one as my "baseball bat" is back to getting nice & fat again. It wasn't getting much water when I watered. The soil had hardened around the rootball and most of the water was just draining out before getting absorbed. I repotted it and used nice loose mix but gave it more room and increased the watering to twice a week. Not it has plumped back up & looks like it did when I first got it. I didn't notice that it had been draining so fast like that as it was in the back of other plants. Now I am making more of a point to check how much is actually absorbed by them.
Marcy