freebsd stable - Feb 2013 - t_delta 16.0106d62009e53600 too long -- Should I be concerned?

Greetings,
 I received the following last night:

Feb 10 23:31:20 udns kernel: t_delta 16.0106d62009e53600 too long
Feb 10 23:31:36 udns kernel: t_delta 15.fefb2d70ffb0bf00 too short

While I'm _guessing_ disk, I'm not sure from where it originates.
Should I be concerned?

Thank you for all your time, and consideration.

--Chris