The pose that moved the figure out of alignment probably had the body alignment moved and saved with the pose.  After that, the body will stay misaligned until you move it, or until you choose another pose that has the body alignment saved in it.

Remember, when you save your poses, if the body's x, y, or z axes have been moved, they're going to be incorporated into that pose when you save it if you check the body transformatioin option.  So if you want to tilt the figure, move the hip, not the body.  That way the body will always be aligned to "polar north" even if you've tilted the body with the hip.