centos 6.10 kernel update ok, grub updated but new kernel isn't loaded

Today on an internal, legacy centos 6.10 server I run > yum update It downloaded and installed, without errors, these packages: kernel-headers-2.6.32-754.15.3.el6.x86_64 Tue 25 Jun 2019 09:46:52 AM CEST microcode_ctl-1.17-33.13.el6_10.x86_64 Tue 25 Jun 2019 09:46:51 AM CEST kernel-2.6.32-754.15.3.el6.x86_64 Tue 25 Jun 2019 09:46:48 AM CEST bind-utils-9.8.2-0.68.rc1.el6_10.3.x86_64 Tue 25 Jun 2019 09:46:40 AM CEST bind-libs-9.8.2-0.68.rc1.el6_10.3.x86_64 Tue 25 Jun 2019 09:46:39 AM CEST kernel-firmware-2.6.32-754.15.3.el6.noarch Tue 25 Jun 2019 09:46:38 AM CEST python-libs-2.6.6-68.el6_10.x86_64 Tue 25 Jun 2019 09:46:32 AM CEST python-2.6.6-68.el6_10.x86_64 Tue 25 Jun 2019 09:46:29 AM CEST I check /etc/grub.conf and it lists as first entry the new kernel: > title CentOS (2.6.32-754.15.3.el6.x86_64) I reboot the server and... > uname -a > > Linux goofy.local 2.6.32-754.14.2.el6.x86_64 In the last months I see other kernel 2.6.* updates, they were fine. Why isn't the new kernel running? How can I troubleshoot this? --- These are the new files in /boot -rw-r--r-- 1 root root 106K 2019-06-18 18:29 config-2.6.32-754.15.3.el6.x86_64 -rw------- 1 root root 18M 2019-06-25 09:47 initramfs-2.6.32-754.15.3.el6.x86_64.img -rw-r--r-- 1 root root 212K 2019-06-18 18:29 symvers-2.6.32-754.15.3.el6.x86_64.gz -rw-r--r-- 1 root root 2.6M 2019-06-18 18:29 System.map-2.6.32-754.15.3.el6.x86_64 -rwxr-xr-x 1 root root 4.2M 2019-06-18 18:29 vmlinuz-2.6.32-754.15.3.el6.x86_64 -rw-r--r-- 1 root root 171 2019-06-18 18:29 .vmlinuz-2.6.32-754.15.3.el6.x86_64.hmac --- > grubby --default-kernel > > /boot/vmlinuz-2.6.32-754.15.3.el6.x86_64