Odd margin on 'alignleft' icons

I’m getting a weird negative-looking margin on the <ul class="alignleft"> in the widget html.
It’s a slight (maybe 6px wide) negative margin on the right side, that looks like it’s creating a space on the left side. I tried canceling it out in the CSS, but I can’t seem to find where the margin is coming from.

See it here: http://davejmoz.com/contact-me/

Any idea what might be causing it?

https://ww.wp.xz.cn/plugins/simple-social-icons/