Shaking preview images

Hi, first of all guys, i have to tell you, you’ve made a great job with this plugin, i think it’s very usefull!
I need your help to fix a little problem i’ve found. I’m using “justified” layout and item style “fade”. Some preview image starts to shake when i trigger the hover effect and the background fade in.
Do you have any ideas about the possible causes?

The site right now is private, if you want to take a look i can send you a temporary guest password in private message.

Thanks