Life Happens.
There are many things in our lives that cause us to move less efficiently. Things like sitting in a car every day during a commute, having our shoulders rolled forward while we type on a computer, or even just some tightness that started way back when and now has just become a way of life and something that you just deal with. Our bodies learn to compensate with what we throw at them but many time this is at the expense of something else in the body.
A stiff ankle may cause you to walk with a limp which could cause your knee and hip to track incorrectly and down the road that incorrect position can take a toll on your body. As always is you are experiencing pain you should consult your doctor to get cleared for any medical issues.