My hips also bother me from too much of the same type of walking. I have to either alternate days for the type/instructor or make sure I'm also stretching hips and psoas area. I love walking, but haven't been able to do so with my PF flaring up again. I've missed my Jenny and Leslie workouts, as well as my treadmill walks.
If I did short mini-walks, I'd probably be okay, but would have to make sure my shoes had plenty of cushion with insoles and support. Other workouts like Slim Series and SI6 also bothered my hips with the number of squats/lunges, too! I just have to listen to my body, and nowadays I do a lot more stretching/yoga than I used to do.