Interesting to read Bune(fat rascal)'s message about loose pelvis and lower back helping dodgy hips. I get exactly the same symptoms as Waterbabe, but when I consciously make an effort to run with my pelvis tipped forward, the hip pain during and after is absent. But be warned, if that is not your usual running position, you will feel quite sick and achey (especially in the knees and lower back) for sometime afterwards as a a result. Well I do anyway - I think it's something to do with different pressures being put on the nerves running through the spine. If you run before bedtime, by the time you wake, you should be fine though!
Now someone will tell me I'm doing it wrong!