I found a couple of other posts that state that the source kernel (for SuSe, anyway) is kept in /usr/include/linux.
I guess the reasoning for this is that the /src/ area is a developers playground. The /include/ directory is for runtime files.
I guess once I read the other notes, it made sense to me. If I could find them, I would post the notes I am referencing. They are floating around this forum somewhere.