4 week old kitten limping

Hello-

I have a couple questions. I rescued a stray pregnant cat a little over a month ago. Got her vetted and babies were born happy and healthy. The kittens are 4 weeks and 3 days old right now. One of the kittens started limping on her right front paw a couple days ago. She is eating, playing, happy, and no signs of her being sick. So I think she just strained it playing. She lets me touch it and squeeze it with no problem, she just won't put pressure down on it. My question is how long should I wait to see if the limping is more of a serious issue? Also, if I do have to take her to the vet, can I take just her away from the mom for an hour to take her? Or do I have to pack all five kittens and mama cat up and take them all. 

Thank you!

Hi

Yay for rescuing!!!  It's a judgment call but if i didn't see improvement in 24 hours or so I would see a vet.  Yes she can be away from mom for a couple of hours no problem.

Stephen