(Next-gen gallery) 28 pixels margin-top

Hello !
I’ve made all the updates I needed today (I usually don’t update :p), and now there’s a little problem. So, I’m using the latest version of : WordPress, Next-Gen Gallery, Akismet and AddToAny. Here’s my blog : http://mirrorsedgefans.fr
The problem appears only for people who are logged in and it’s just that : a 28px space above the banner [url=http://michawha.free.fr/la/vrac/banniere.jpg]here it is[/url].
I’ve been looking for the origin of the problem and when I take a look at the source code of the page, juste before the </head>, I see that :

<meta name='NextGEN' content='1.7.4' />
<style type="text/css" media="print">#wpadminbar { display:none; }</style>
<style type="text/css">
	html { margin-top: 28px !important; }
	* html body { margin-top: 28px !important; }
</style>

So, looks like it comes from the latest version of NGG, but I can’t find any file that contains this code :/
So if someone can help me, thank you in advance.