[CentOS] Broken upgrade to memcached

Yum checkupdate tells me I should update memcached, that the x86_64
1.4.5-1.el5 needs an update, I go to do that, and it complains that it's
missing a dependency of libevent-1.4.so.2 (this is all 64 bit, CentOS
5.4).

Clues... or is this actually broken?

       mark