ckeditor inline editor graphic glitch

sometimes when exiting edit mode from a ckeditor inline edit session, a strange pattern appears under some or all of the images which looks like this

refreshing the page seems to clear it most of the time, but it's disconcerting for editors and we've had one person manage to get the glitch to stick to the page

it seems to be a span

<span style="background: url(&quot;http://intranet2/javascripts/ckeditor/plugins/widget/images/handle.png&quot;) rgba(220, 220, 220, 0.5); left: 10px; top: -5px; display: block;">``

that is somehow based on the image grab handle?

anyone else seen/fixed this?

thanks