I can't figure out why the text is not in dead center of my black screen. Looks a bit up. It have been entered with the align tool, but for a reason or another, to me it looks a little bit up.
This is an optical illusion.
The weight of the lower text is pulling your eyes even when not focusing on it. Its a concept called "optical center," which is well documented. The mathematical center will never look properly centered. This is where knowing software isn't the same as knowing design.
here's a quick demo.
this article covers it pretty well.
Page (and screen) layouts often start out mathematically on a grid or geometric pattern of some sort. But nearly all designs need 'optical adjustments' so that they look correct.
In your case, the type is likely mathematically centered, but not optically.
If you feel the type is a bit high, nudge it down.
I can't really tell from your picture, but I've encountered similar problems and I don't think you're imagining things. If you want the short version, Illustrator centers text based on the bounding box, not by the width or em height of the font.
The various rectangles in my example are sized to be exactly the em height (blue), total height (green), and width (pink) of the text. You can see that though the border around the text fits neatly in the green rectangle, the text inside the bounding area is not vertically centered. It's not even quite horizontally centered.
Whenever I have to vertically center text I create a rectangle that is the same height as the actual text (not the bounding box!) and I center that. After that all you have to do is line them up with smart guides. (There are probably better ways to do it, though)
I think this is an optical illusion mostly.
When I need to align text similar to this I usually copy the text, paste in front, convert to outlines then group. This way the bounding box isn't being used. I then use the align tools and lock the Group. Afterwards I position the live text then unlock the outlines and delete.
I'm sure there are many ways to get to the same conclusion. -Andy