Hey, this is actually intentional but thanks for letting me know anyway! I made it so there is a small chance for a cluster of "live" cells to appear in a random location every now and then, which I think is what's happening in your case. This definitely isn't the default behaviour for Game of Life, though I suppose I wanted to make it so that it wouldn't just end up in a state where the whole thing grinds to a halt and never does anything again!