Normally I would still be playing, but we lost our field and are in the hunt for another; otherwise we play until the snow hits (about November, December). I'm doing a lot more kicking the heavy bag, core stuff, weights and am being drafted into yoga by a very aggressive yoga instructor at my work.
After your post, I was trying different stretches, etc. that would cause any discomfort in that area as a test - not overstretching, just seeing what would give me a twinge. There is one exercise that I do, where I do a kick slowly and hold it extended. I tried several different kicks, the one that gave me a slight twinge was a front kick on my right (less capable child): as I extended it to its full extent and held it suspended, I felt a bit of inner groin irritation.
It went away the moment I released the leg, but it was there. I tried it on the left, no problem - it seems that I need a little work on this, so will do what I can to make that side act as the left does. So even after two years, there are little twinges there if you look for them. I don't mind improving things, though.
If you look at the physiology of the psoas, it is attached at the groin area, but goes through to the lower back. It could be that the lower back pain is tied to psoas irritation.