[CentOS] 5.4 kernel versions?

Please excuse a possibly dumb question.
Prior to the release of CentOS 5.4 I believe two updated 5.4 kernels 
were released as part of 5.3
2.6.18-164.el5 and 2.6.18-164.2.1.el5
Now that 5.4 is released we have just the 2.6.18-164.el5 kernel.
Now the dumb question - what happened to the updated kernel?
I now have workstations running 5.4 with the 164.2.1.el5 as they get yum 
update run regularly, however I do not reboot my servers as often and 
now find these do not have the later kernel.
If some kind soul would please enlighten me.....
Rob
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