I have an odd black speck on my Acer Aspire 5's screen. Its 1px by 1px in size. It is white when the screen is off, so not a dead pixel. It is black on white screen, and whiteish on black screen. It is slightly raised when I run my nail over it.
Since its there when screen is off, its not a dead pixel.
From the picture it sure looks like a dead pixel. But it you say you can feel something slightly raised there, you might want to use a little bit of of soap and water to wet a paper towel an see if you wipe it off.
You are probably correct and there is not much you can do about it.
Possibly look at an automotive product that is used to fill in cracks in a windshield.
Filling in the pit with something clear might make it look better.
There is a real risk that you will make things worse so consider that option carefully.
Since it looked ok before you wiped the screen, there is some hope that it will look ok to you in time.