I am using CENTOS 4.3 - kernel 2.6.9-42.0.2.EL with rkhunter version 1.2.8, but the rkhunter program show me problem on file /bin/kill.
I had the same issue and asked on the rkhunter mailing list. RKhunter is currently under new ownership and they are starting to fix issues like this. v1.2.9 is out now and in the mean time you can manually use hashupd.sh from the website [1] to update the rkhunter has database.
Oh and RKhunter uses prelink for the hash check so the hash should be constant when libraries are updated :-)
Dan
[1] New RKhunter home http://rkhunter.sourceforge.net/