Possibly you moved some furniture in there, causing crease? Perhaps weave relaxed a little over time. Probably not stretched enough in installation, though. I think you're going to have to re-kick it, either hire a pro or diy. You can rent tool at HD, I believe. Try to see which direction(s) it needs to be stretched. You may have to pull off baseboards where you are going to lift carpet off tack strips (probably at 3 sides of room), but first try to see if you can lift it w/o doing so. I believe you start kicking from the center to pull out crease, then work toward ends- better ask about that, though. You may have to recut once crease is pulled out- use very sharp strong blade- push straight-edge in fold at baseboard, cut leaving enough to tuck under baseboard. Don't cut too much! Can be easier if you do pull off baseboards- you'll be cutting at wall. Forgot to say push back on to tack strips using board or some object- not your hand(ouch!).