What does cc -dumpversion tell you?
What gcc version is listed in /proc/version (this is the gcc version used to compile the kernel)? These should be the same, or it would've complained earlier, but you never know (you didn't use IGNORE_CC_MISMATCH, did you? Don't ever use that unless you KNOW it'll work)...
Are you sure your kernel-source is installed correctly? rpm has an option for --query that will look at all installed files and recalculate their checksums against the original RPM package's checksums. Run that on the kernel source package to see if it matches up well enough.
You might also try running a make oldconfig from inside /usr/src/linux-<version>