Hmm this is not rare. See the 4th move of white in this game also.
It seems it is just a display bug as players seemingly can't "hit" the blot and as one can see later in the game(6th move) when the white checker leaves that point the black checker is revealed again.
(sakla) If you need to find an older message from the selected user, click on his Profile and use the "show this user messages" link at the page top. (konec) (Bütün ipuçlarını göster)