Seems to be an issue with red hat
Refer to the answer on this post-
https://supportforums.cisco.com/discussion/11323611/ntpd2591-ntpfrequency-error-512-ppm-exceeds-tolerance-500-ppm
First thing I would try is restarting ntp service. It should be "utils ntp restart"
If those error messages persist in the log, I would continue with a system power cycle.