Could be that she's not drinking as much as the others, and you've overwatered her. I do this often, cuz I'm an idiot.
- Or that she's drinking a lot more than the others, and she's thirsty. Which isn't a big problem, overwatering is a lot worse..
If you've just watered, there's nothing you can do. You're gonna have to wait til soil dries.. You have to check the soil pretty often to know when it's drying up, lift the pot now to get a sense of the weight, and then check it again and again, until you can feel that it's getting lighter.. You won't know by looking at her, since she'll go from drowning to being thirsty pretty fast, which is very close to the same symptoms.