Mintee
the butter or fat probably congeals and makes it seem gritty.. just warm it up again and give it a good whip with your spoon
kswck2
You have made them incorrectly.
denise
Well, they are fluffy / creamy when hot so, when they go cold and hard they change texture.
Anonymous
I've always thought the moisture pulls away or separates and makes it appear grainy. Once you reheat and stir it up is regains its smooth consistency.
Bone Alone
Something to do with the starch.