Hi Lou,
This could be a minor issue or indication of something larger potentially. A simple explanation could be similar to the tingly feeling you get when you sit on your foot or basically your “foot falling asleep” but since we can’t ask your dog, this is a broad assumption. Playing on the cautious side, it’s never a wrong idea to have her checked out by your veterinarian primarily for any bone defects or joint abnormalities such as a luxating patella which can be diagnosed in dogs of any age.
I hope this helps,
Dr. Ryan Llera