Preoperational Egocentrism? You Be the Judge

My sister was chaperoning a field trip of kindergarteners. On the bus on the way back the boys were playing "I Spy," including this hilarious gem:

"I spy something green."
"Your sneaker?"
"No . . . "
"Your other sneaker?"
"Yes!"

Piaget says that from two to seven kids usually show "preoperational" forms of reasoning. One of the most childish logical lapses of little kids, from an adult perspective, is egocentrism - that is, the kid's belief that everyone sees things the same way the child does. I have seen film of a wonderful experiment in which two kids are looking at an identical array of oddly shaped objects, but they can't see one another. One child is then supposed to describe one of the objects, so the other one can pick out the identical object. An adult doing this experiment might say "I am looking at the red ball," which would be readily understood by another adult looking at an array that included one red ball. A little kid, on the other hand, is likely to say "I am looking at this one." The other child might reply "So am I!" - though each is looking at a different object, with no idea what the other means.

So, is the above exchange an example of preoperational egocentrism in kindergarten boys, or an ingeniously subtle way to play "I Spy?"