Ok, check out the contents of /etc/crontab. That will tell you exactly when the contents of cron.daily are executed. For example, my crontab file has this entry for cron.daily (Red Hat 8):
02 4 * * * root run-parts /etc/cron.daily
That's saying that everything in the cron.daily directory gets executed at 4:02 AM every day. If your computer is not turned on at 4:02 AM, then cron will miss that opportunity to run the jobs. So, if you're in the habit of turning off your computer before going to sleep, then it will never get run, and consequently give you the "out of date" message for the database. The solution would be to add the updatedb command to your startup sequence (which might add a significant amount of time to boot), run it manually, or change the time the cron.daily updates are run to sometime you know the machine will be on.
If you're really only after the last time the database was updated, you can check its modification time. On my system, it's located at /var/lib/slocate/slocate.db