R.M.
Does she act like she is having any pain at all in her back, hips, legs or feet? Will she walk when you hold her hands? My guess is that this is just a reaction to your being gone to school and she has found that not walking is a great way to get attention. I would not make too big a deal out of it, definitely don't discuss it when she is within earshot. ( children understand a lot more than we give them credit for!!! Mention it to your pediatrician the next time you are in but my guess is that this is just a stage that will pass.