Ok, actually it seems that it does pick up the valid width and height. I just had them reversed when adding to the database blush.

Here's the fix. admin/doaddgraemlin.php, line 86 looks like this:

$query_vars = array($code,$smiley,$graemlin_name,1,$imagewidth,$imageheight);

That should be this:

$query_vars = array($code,$smiley,$graemlin_name,1,$imageheight,$imagewidth);