Minor bug I've had for quite a while, ever since I started using skill mods. Selecting anything in the way of your skills with non-vanilla skilks available and then hovering over, and in particular deselecting a skill again from your selected skill bar makes the icons for the skills you have kind-of glitch out. It's not a major thing, but I thought I would mention it.
It's been like that for me since mod support was added. It never bothered me enough to mention it, since it's only cosmetic. I thought that maybe it had to do with my resolution or something like that.