My brothers cat has been staying with me, she got knocked up (don't get me started on why he won't fix her and why I'm taking care of her kittens) her babies are just over 4 weeks old, we started giving them mush food a few days ago, only one is really interested in it, a couple other munch a bit, but we haven't seen them poopie or noticed any on their blanket. They're healthy happy goofy little babies. I've dealt with litters before, and they were always little poop machines, these ones don't poo and I'm a bit concerned about it. Mommy licks them to help stimulate, but nothing. Could there be something wrong with them?