Ditto, Yap Yap, I have the same thing. Went to see an osteopath last night, my longer leg has been over stretching my hamstring which has been ok while I've been plodding along for the last year since i started running, but when I introduced some sprints this year it proved too much and my hip became too painful to run. I'm getting some manipulation done and then a stretching programme. The good news is if I keep the stretching going it should not hinder me in future.
I hope, Great North run looming up and no running for the last month!!!