As long as it's slow and relaxing, go for it! The only drawback is that if you start walking too fast or turn it into an exercise-like jaunt, your body will start to produce adrenaline and you won't be able to fall asleep very easily. (It's why they always tell you not to exercise before bed.)
But as long as you become relaxed and it helps clear your mind, why not? Sounds like a great idea to me.
