front or back? I would ice tonight and after your run tomorrow. Be careful!!!! I ran a half marathon in June and then had a few "twinges" in my left posterior thigh, rested, iced, was pretty gentle (as gentle as I could be as I had started full marathon training). Long story short-went for a light 5 mile run and at mile 1 felt an ugly pain, pulled up, thought I could shake it out, tried to run again, realized I needed to get off it, went home, iced etc. went to the doctor the next day and found out I had a torn hamstring. One month off it, 4 weeks into PT and I am just starting to run again. Good luck, listen to your body and be careful!!!!!!!!