Mother cats will occasionally look for another place to move the kittens to.
For one reason or another they don;t feel happy with the present place and
she will revert to her instincts and move the kittens from the "danger". If
you can let her settle with the kittens in a new place she chooses if of
course the place is suitable. Perhaps give her a big box where she can hide
into with the kittens with some cover/bed spread/throw to lie on.

The reasons can be any number of them, usually the place is far too crowded
for her liking, maybe too many humans or too many kids or other pets. Maybe
the music or draft or some smell, could be anything really we can never know
for sure.

Perhaps in a couple of days try and move her and the kittens back to the
best spot you think, but make sure is comfortable and safe for kittens and
gives mum rest and peace she so needs and deserves.

When my Tiara was born, and made a hole in big box and turned it upsade down
and put it on my double bed. For the next 4 weeks I slept sideways but never
enjoyed the time more, I just wanted to soak every second of it. Mum did
take the kittens elsewhere once, but we had to move them back as place she
chose was really cold.

Gee

mommy knows kitty little is food

Funny, I just went through this.  Had mom and babies in an excercise pen in
my room.  She was content and happy there for two and a half weeks.  The
other night she decides to relocate them to under my bed.  Ok, they were
safer in the pen than under my bed - at least in my mind they were, but I'm
only a stupid human.

I blocked the top of the pen, she paced with a kitten in her mouth.  Then I
tried putting her and babies in large dog crate - kitty litter everywhere,
flipped water dish and kittens helter skelter.  Finally mom and I
"compromised" - she is next to my bed out in the open with her own little
cat bed.  She seems happy there.  Babies will start to explore soon (they
will be three weeks tomorrow - so cute, starting to learn how to play).

So long story short, they will move them, and sometimes it escapes human
reasoning why one spot is preferable over another. <smile>

JoJo