My cat had kittens a week ago, the kittens stay in the shed, and my cat comes in to the house to be fed. Whenever she is indoors, she tries hiding in the most random of places, which she didn't do before. She'll hide behind cushions on the sofa, the bottoms of wardrobes, and on shelves in behind ornaments. She doesn't seem agitated or stressed, why could this be?

She is probably scared of the Tom cat or she is just getting ready for something

If you allow her to go outside, please plan to get her spayed as soon as possible, or she will produce another litter of kittens the next time she goes into heat.