If it's just tight and achy, you may want to just try stretching it more, doing some leg lift type exercises, and getting one of those foam rollers that you lay on and rolling on your thighs and IT band.
If it's causing you significant pain, I'd recommend seeing an orthopedist to rule out anything serious. (Edit: a number of martial artists I know, myself included, have had to do PT or even orthopedic surgery because of torn ligaments, damaged cartilege, etc.)