I've been wearing asics nimbus runers for the last year and I need a new pair. I've been happy with them up to now, but I've noticed in the last couple of weeks that after an evening run or walk, my akles are very stiff the next morning and it takes a few mins of walking to get them right again. They aren't sore. Do I need a gait analysis to see if I need a different style, or is this reasonably normal? I don't run very far or fast but I try to do it 3-4 times a week.