I've noticed Facebook has been doing a lot of AB testing on me lately. [Example: My Graph Search bar is now White-on-Blue instead of Blue-on-Blue. Also, the sidebar with birthday notifications used to display Friend Requests that told you who Friend Requested you; now it's gone.]
This spacing behavior is likely also a part of that. It just happened to me very, very recently, and there used to be sufficient padding in that UI location.
It's happening to me too. Every day something looks broken (read different). The Facebook logo was not centered before the graph search for a couple of days, the height of the chat box was changed and same goes for the padding.
All I hope for them is to remove (or shift) the video chat button. I've had lots of accidental clicks on it.
This spacing behavior is likely also a part of that. It just happened to me very, very recently, and there used to be sufficient padding in that UI location.