it could be your your fastest mirror plugin is chuffed... worth having a look to see if there is a corrupt entry.
Mine looks like;
[main]
enabled=1
verbose=0
socket_timeout=3
hostfilepath=/var/cache/yu
m/timedhos
ts.txt
maxhostfileage=10
maxthreads=15
#exclude=.gov, facebook
timedhosts looks like;
fr2.rpmfind.net 0.0758020877838
anorien.csc.warwick.ac.uk 0.0633990764618
mirror01.th.ifl.net 0.0577881336212
mirror.as29550.net 0.0609180927277
mirror.netweaver.com 0.0572769641876
apt.sw.be 0.0638451576233
mirrors.manchester.icecolo
.com 0.0803859233856
ftp-stud.fht-esslingen.de 0.074826002121
mirror.ox.ac.uk 0.0466530323029
mirrors.melbourne.co.uk 0.0573019981384
mirror.bytemark.co.uk 0.0452480316162
www.mirrorservice.org 0.0527808666229
mirror.sov.uk.goscomb.net 0.0472700595856
mirror.ukhost4u.com 0.0568220615387
mirrors.dedipower.com 0.0641639232635
mirrors.ukfast.co.uk 0.0727400779724
you could try uninstalling the packages again, though you will need a copy locally :-)
# rpm -qa | grep yum
yum-utils-1.1.16-14.el5.ce
ntos.1
yum-metadata-parser-1.1.2-
3.el5.cent
os
yum-3.2.22-20.el5.centos
yum-fastestmirror-1.1.16-1
4.el5.cent
os.1