I just got a new pair of shoes for X-mas, and I tried them out on an easy four mile run X-mas day. They felt real comfortable, but I noticed them a lot softer than my older shoes. Older shoe: Nike Pegasus 2007 w/bout 200 miles in them, New shoe: Mizuno Wave Rider 10. I woke up with a sever pain on my left hamstring, possibly strained. Could this be from the new shoes? I don't want to return them, I like how they feel. I haven't ran hard in weeks, just been running 4-6 miles per day, easy 7:45 pace. I'm not injury prone, and I have never had any issues when changing shoes, but I have always changed to the same ones. Anyone with similar problem?