[CentOS] Mysterious versioning reported by file command

I just noticed this, which doesn't actually seem to affect anything but does create a mystery:

[frankcox@mutt temp]$ cat test.c #include <stdio.h> int main(void) { printf("Hello world\n"); return 0; } [frankcox@mutt temp]$ gcc -o test test.c [frankcox@mutt temp]$ file test test: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, not stripped [frankcox@mutt temp]$ uname -a Linux mutt.melvilletheatre.net 2.6.32-220.17.1.el6.x86_64 #1 SMP Wed May 16 00:01:37 BST 2012 x86_64 x86_64 x86_64 GNU/Linux

Why does the output from file say "Linux 2.6.18" when the actual kernel in use is 2.6.32?