Quoted from lordnorth:

DISAGREE. You walk away from a machine only when you are done playing. If someone lets credits on a machine, you can bet your ass I'm going to be playing them. How do you figure you have rights to credits on a machine that you walk away from? Using that logic, if you were to put in 20 or 30 credits you would be allowed to come and go playing the game a few minutes at a time for an entire day? "Yeah... I know I went to lunch for two hours... but I still have credits on the game..." Doesn't matter if it is 2 minutes or 2 hours. You walk away when you are FINISHED.