There have been reports (even amongst Gamereactor's readers) that some PlayStation 4 units are randomly ejects discs while playing, or start beeping for no apparent reason.
It seems the complaints have been high enough in volume for Sony to act on the issue, and therefore they have now released a video that shows how most of these issues can be solved pretty easily. If the steps shown in the video don't help, Sony says that you should contact them and arrange for a repair.
Thanks, Destructoid.