As for strength, I think that could be part of it too. I only started doing deadlifts again this last summer, and then I had to lay off them while I was rehabbing my MCL injury. And as you know, I've just begun working the squats back in for the last few weeks. I gotta get more serious about my plyometric boxes too, now that my MCL is good to go. Maybe the plan for December should be doubling up my deadlifts and squats, doing them on Sunday as well as Wednesday, and keeping the runs short and fast. Whadaya think?
Also, in that ITBS thread, Dama mentioned that hills seemed to trigger it for her. Have you found this to be true, or have you heard this happening for other folks?