(Very) new kitten suddenly shy

Hello.  Hoping for some advice as very new to this.  We brought home our two new gorgeous kittens yesterday.  Both are around 14/15 weeks and from the same breeder so have been brought up together.  They were pretty active yesterday, exploring and playing in the room we have set up for them for now (food, water, toys, litter tray etc).  Neither of them seemed to eat yesterday but they used the litter tray and we saw them drinking. 

Last night one got scared (I think it was the noise of the vacuum in another room, although they are used to vacuums from their breeder).  First she hid right up in the back of the sofa but we managed to coax her out.  She's spent a lot of time now hiding under a small chest of drawers.  I saw her eat a bit of wet food this morning but nothing since then.  She doesn't come out for toys like she did yesterday, but  I can see her watching them.  She is happy for me to reach in and stroke her, and is also washing herself. 

Does this sound normal, or should I worry that she might be sick?  She seemed to be the more adventurous of the two yesterday but now she just doesn't want to come out of her space.  The other kitten, in contrast, is coming out to eat, play, cuddle etc.  I do realise it's all new for her, but don't want to miss something. 

Thanks for your help.

It's normal for some kittens. She might explore when you'r not around or asleep. Give her time and she'll follow her littermate and come to you.

When I brought my 12 week old rescue home last July I put her in a quiet room. A little later I went to look for her & it literally took me 2 hours to find her in a tiny crawl space underneath a bookcase. Even when she came out into the rest of the house her favorite spot was under the bed. One year later, she is much better now, but still skittish. Her new favorite place is a crawl space behind our bathtub. I love her to pieces though with all her funny ways. Your kitten will be fine. Try to imagine how she feels & just give her time.