Maybe Sick, Maybe Over-reacting

I have a mini rex who's always sweet and snuggly for a baby. She's always been calm, but does enjoy chasing her sister and our other rabbit around the house once dinner is done. She seems kind of lethargic and it's making me nervous because I've been searching for answers and can't find anything for this specifically. The vet's office is closed, but this is the only symptom she has. She's ate well all day and I'm not sure about water intake due to the fact that all 3 rabbits share 4 water bottles/bowls. We have two cages in a little room that each have a bottle and they remain open for access between the two as well as two water bowls placed around the house so I don't know for sure if she's been drinking her usual amount, but I have seen her drinking. I know she's eating. Poop's been normal, but I'm not sure about urine because they all use the litter boxes as well. Is just being lethargic cause for concern or am I over-reacting?

What makes you say she is lethargic? How is she actually acting?

If shes eating/drinking as normal and following that with pee/good poop then I think you're good. You may need to separate her if you think she is not doing one of these things just so you can observe her actually do it.
How old is she? Are all 3 rabbits altered? Any altercations?