Is the dot maybe just one pixel wide by one pixel tall? I've had one pixel be a solid red or blue color on my LCD computer screen maybe 3 or 4 times. I just tap the screen with my fingernail in the area and the pixel turns back to the color of the rest of the screen.
Some are two wide, most are one wide, none go away or anything with the stylus/fingernail tactic. I tried a few things, uninvasive, nothing.
