Yes, this seems to be a bug, I hit it after updating.
It does step to the next line though, it just doesn't update the highlight and current position.
Over the last few years I've experienced quite a few of such annoying bugs in Eclipse IDE for PHP Developers (PDT) with official updates. One might get the impression that the developers don't pay much attention to regression testing.
If you've updated Eclipse recently, open "Help" -> "Installation Details". Click on the tab "Installation History" and find an entry that doesn't contain version 4.4.1 (it's 22.214.171.12440612-0500 here).
The Eclipse project page is a bit messy in my opinion (or I'm just blind), but you can fortunately crawl a mirror site to find older releases: