I've lost 4 pounds?

I was silly enough to weigh myself yesterday while at the gym.  I know I've lost muscle but I'm wearing a heavy cast so you think they would make up for the lost muscle.  I'm down four pounds and feel maybe a tad more fit then before (not cardio, but strength).  And since I do about 30 min of abs a day I finally have a flat stomach.  Goodbye Creighton Belly.  I don't know if I am allowed to do all the exercise I do but I'm not stopping now.  Here is a selection of Wallmart DVD's that have stopped putting the weight on.