Recently (last day or two) LJ appears to be substituting a different icon for my default; it seems to happen most often when I'm commenting. My default is a photograph of an actual Sea Wasp (in color, blue-green with trailing tentacles). The one it's substuting in is labeled "a disbelieving Doctor" and shows a somewhat goggle-eyed Tom Baker.
When I go to edit the message and change the picture, I can't even SELECT my default icon. And if I change to a different icon and then try to switch to the default, it just keeps whatever I selected, not my default.