I bought a 16Gb 4th gen nano at a pawn shop and it had this unusual screen dot on the LCD, never really bothered me, been using it off and on for about a year, today I noticed it was gone. Kinda strange.
In the Gameboy world we call that screen cancer - oddly enough I’ve had it go away on me as well, even though it’s not supposed to! Glad it got all better!