How's your sleep position ( do you sleep on your side or stomach )? How much sitting?
Hang from a bar or rings and do sideways straddle swings and hip circles. Can help and loosen things up. Good for shoulders and neck too.
I've always been partial to doing seal stretches and yoga plow thingie in my warmup besides those side twisting things ( scorpion? ) or windshield wipers on back. A lot of this was caused by a lot of sitting in my car during a commute, I think.