broken ankle cast too loose?

hi so I recently broke my ankle, first ever broken bone, unstable fracture of course so I had to have 7 screws and a plate put in. anyways. it hasn't really hurt more than my normal arthritis pain and honestly for the past week or so it's barely even ached (in the third week of recovery now) but I've noticed my cast I loser than it was when they put it on on Tuesday. im 50 percent weight bearing at the moment as instructed by they doc but it feels.. stiff in the joint? I mean I shouldn't be able to even feel the stiffness because I shouldn't be able to move it but like it's that sort of pain you have when you try to move your neck after sleeping weird. I don't know if I should go and get it recasted (it's free if I do) or if I'm just worried over nothing.