The CMS holds a cache of the data that the Player needs when it connects. All the time that there’s “no change”, then the CMS can serve that cache to the Player which greatly reduces the work the CMS needs to do each time.
However, sometimes, a change you make in the system should result in a change to the Player, but the cache isn’t properly cleared. Eventually the cache expires and the problem would have rectified itself.
We have one open bug regarding this at present. Do you by chance use Campaigns on that Players schedule? And if so, was the change to a layout in a campaign?
Otherwise if it normally works, it could just be a one-off thing that won’t reoccur.