First thing to realize is that even once you get as limbered up and flexible as you can for your body, the stretch you have in your hip area and hamstrings is not going to be the same everyone else you paddle with. It is pretty individual. I can take nearly straight legs, but have been out with excellent paddlers that can’t match my angle without pain. I just happen to have more flexibility in my hips than the average bear.
Second is that you likely were tense and making it worse, like anyone else would have been in your place. One concept with edging that reduces tension is to not try and edge by applying muscle to lift either side of the boat, but to slide your butt a bit into the bilge and let your weight put the boat on edge. But that is a leap of faith for someone starting out, to be over in the water and stay relaxed. If you had a lot coming at you I doubt that was going to happen.
If you were pulling to one side a lot you likely were getting some weight off center, but with trying to keep all the instructions straight you were not aware of it. I suspect that as you are able to relax more you will find a lot of this abates.