I've known about this for a long time; it's been around way before v13. As Jimmg mentioned, the face changes back to normal after a few seconds. Also, it's safe to assume that this was added intentionally considering this is in the fillcan server.cs file.
$face0="smiley";
$face1="asciiTerror";
$face2="memeBlockMongler";
$face3="memeCats";
$face4="memeDesu";
$face5="memeGrinMan";
$face6="memeHappy";
$face7="memePBear";
$face8="memeYaranika";
$face9="smileyBlonde";
$face10="smileyCreepy";
$face11="smileyEvil1";
$face12="smileyEvil2";
$face13="smileyFemale1";
$face14="smileyOld";
$face15="smileyPirate1";
$face16="smileyPirate2";
$face17="smileyPirate3";
$face18="smileyRedBeard";
$face19="smileyRedBeard2";
$facecount=20;
function resetface(%obj){
if(!isobject(%obj))
return;
%obj.setfacename(%obj.client.facename);
if(%obj.client.accent==1)
%obj.setnodecolor("visor",%obj.client.accentcolor);
I don't claim to know a lot about scripting, but I'd assume that if it mentions faces, then it was meant to do that.