This simple code produces the result in the image below.

function setup() {
  createCanvas(windowWidth, windowHeight);
}

function mouseMoved() {
    if(pmouseX !=0){
    line(pmouseX, pmouseY, mouseX, mouseY);
    }
}

function windowResized() {
    resizeCanvas(windowWidth, windowHeight);
}

There are a lot of lines ending in points where mouse never was. The ones looking like a "hair" or a dragon's scale :) It should be pretty obvious running the code. The same code in java does not produces this artifacts.

I found that here. And isolated in the code above. In this page it happens rarely and in a different pattern. several lines are draw form the same start point. The pink line in the second picture below.