My cat had 3 kittens exactly 1 wk ago 2day. Suddenly today she has started hiding them in my closet.?

For a wk she has been content w/ the crate she & the babies have occupied. There is a heating pad in place to keep her & the kittens warm; the rm they are in is private & secluded; the papers & towel in cage are carefully cleaned every so many days by only me. Why would she suddenly be insistent on placing them in my closet? Is this part of the weening process? @ 1st it was just 1 kitten & I thought maybe that kitten was sick but now she has brought in all 3. Any ideas what might be going on? She & the kittens have been left a lone as much as possible so I don't believe she feels they have been threatened. Any suggestions would be greatly appreciated.