Fullness while walking

Yesterday, I noticed, while walking, that, as I let go of the muscle more and more, the tissue around mingmen would release. It felt like it was moving away from mingmen in everydirection and around the torso to the front. The yin surfaces on the torsoall becamed very heavy and dense like wet wool. The belly became very full and hard with no effort. I can't reliably reproduce this effect. I can most easily find it while walking around, but it is near impossible to find it when I'm standing still or trying to train. Advice please...