Ok if there is no real pain, then I would say that your body is just adapting to the exercises... if you do start getting pain. take some anti-inflams and ice that bitch till the pain subsides.
that pulling type pain sounds like you might have a tight muscle somewhere? my guess would be ITB or glute, but who knows, you could try using a foam roller on your quads and glutes. and keep squatting deep and soon you will be doing it as easy as breathing...
Hope that helps,