Take it slow. Hips are slow to loosen up.
I just ordered a leg stretcher. The device is designed to improve your full splits. I've wanted one since I was a kid watching JCVD movies. When I was younger and practiced Tae Kwon Do, I could easily throw a kick over an adult's head; cold.
Now - older, heavier, and with more muscle, I'm as stiff as a board!