I was told I have QL tightness by my MT/PT. I hadn't gotten injured, but he said it could easily cause injuries if I didn't take care of it. The only negatives I had ended up experiancing relating to this (before I visited my MT/PT) were shooting pain in my glutes sometimes after 15+ miles (due to the tendon that connects the QL to the glutes) and (also after 15+ miles) slightly restricted arm swing due to lower back tightness (which was the QL).
What makes the QL a finicky muscle is that it lies to the sides of the vertebrae, so it is generally ignored when people are rolling out and stretching. After my appointment, my MT/PT told me to roll out my L and R sides of my lower back with a tennis ball and add a QL stretch to my routine (while involves standing with your back to a wall with legs a little bit more than sholder width, then resting your L arm on your L quad, perpendicular to the leg, the L leg/foot parallel to the wall. Then with your R arm, reach it over your ear and bend your upper body towards the L. You should feel a pull in your lower back to the R over your vertebra. Then, switch sides.)