What does Jonas see in the apple while he is playing catch with Asher?

What Jonas sees in the apple is a bit of color.  He does
not really realize what he is seeing, though.

This happens
very early in the book.  All that we are told is that somehow the apple changed.  When I
first read the book, I had no idea what sort of change was going on at that
point.

Much later in the book, the Giver will tell Jonas
about color and Jonas will realize what it was that he was seeing.  But at this point in
the book, he has no idea what happened with the apple.