Jim!!
Cute story!! I bought a kong a long time ago for my westie and my poodle but I didn't use it much and they didn't seem to care for it. My poodle doesn't really "play with toys", but I will definately get one today when I go out because it sounds like yorkies really like them. What size did you get? I heard someone describe it as "snowman" shaped. I know it is sort of hard to describe to someone!!
Anyway, It's been three days, do they still play with it and did you get a second one?