Morning when I turned on the display it showed a white vertical band

I normally close the lid of my laptop at night but it remains on.
Yesterday I forgot to do so. It shuts off the display but is set not to shut down or sleep or turn off harddrives.
When I move the mouse I see a white vertical Band exactly the 1/4th the size.
Now to be clear the problem does not exist anymore It has become allright But i want to know what caused it if it is a hardward problem as my laptop is still under warranty I can replace the laptop if the next time it does the same thing.

So I don't have screenshots or photos but I recreated them in photoshop as it was pretty simple.
Here is what happened in sequence.

1. I have a another monitor connected which was working perfectly This Laptop display showed this and would not turn on nothing would appear.

2. Then I was fiddling around I tried touching the edges tapping it to see if there was any loose connected but it did not seem like it. Nothing changed from what I did I could see a lot of bleedeing from the edges which became more prominent and now 4 bands appeared of equal width like below by itself as I was browing the internet on the extended monitor looking for some solutiosn.

3. Then I restarted the laptop and I could see the Bios logo with the same band but now it was bit lighter Then the desktop was visible everything was fine the band was lighter.
Like this

4. Here I found that The Laptop screen is using the Intel graphics card. while the Extended Monitor is using the Nvidia Graphic card. So I found there was a driver update for the intel and updated it.
There was no change I restarted the laptop a few times it started to get lighter the band or at least it seemed.
I work no the extended display. So when I was searching online for help I noticed the band had changed it had dropped from the top around a centimeter like below.

Then I kept searching for more then I pressed my screen after a few minutes when I looked back at my laptop screen it was gone. I restarted the laptop a couple of times Even the Bleeding now is less (as much as it was when I got the laptop there is a slight bleed of white light on the right which I checked is pretty normal for this range laptops) Then the laptop was idle so the screen turned off when I turned it on it was perfect.

So If anyone faced this I would please like to know what causes this. If it is a weakening Display card (In this case the intel which is embedded in the Motherboard) then maybe the next time it happens I should try to get a replacement?

Is something causing it.

Just for the record nothing fell on it the laptop was working find at night I just went to lie down and fell asleep in the same room the laptop was not touched at all no chance anything fell on it.

Thanks.