
I notice this sometimes and it's when the pups are moving into position to be born, so maybe they are in a better position for her to walk about. My last girl to whelp galloped around right until the end with this pregnancy (4 pups), but her in previous pregnancy(5 pups) she gave up running quiet early on, so it's different every time. If you can feel movement that should reassure you.
Good luck with your puppies.
Liz