It's a PlayStation 4 firmware update day – but not one of the good ones. Sony's sneakily launched system software v4.55 today, which improves the stability of your console. In other words, it's bringing some behind-the-scenes bug fixes and not a lot else.
The patch weighs in at just 339.9MB so shouldn't take long to download. It also appears to be optional so, while we'd recommend you install it as soon as possible, it shouldn't interfere with your scheduled gaming sessions.