Cannot reproduce on en.wp with Firefox 36 on Fedora 21. Looks like "Previously" here.

(Plus no deployment since March 25 on en.wp (except SWATs that I didn't check) and don't see anything in https://en.wikipedia.org/w/index.php?title=MediaWiki:Common.css&action=history about .mw-notification-area either.)

It's now visible at beta: http://en.wikipedia.beta.wmflabs.org/wiki/Main_Page

No longer visible at enwiki. Screenshotted:

Confirming, and on en.wp in Vector skin I see this CSS for positioning:

.mediawiki .mw-notification-area-layout {
  top: 7em;
}

while I don't see that CSS on en.wikipedia.beta.wmflabs.org.
But there's also the difference about the addedwatchtext string that I have no idea about.