It’s not a race but people do keep track of the relative popularity of various distros of GNU/Linux. After years of being at the top of the heap on Distrowatch, Ubuntu has been passed by Mint and Fedora. At the same time openSUSE passed Debian GNU/Linux.
This may be just a glitch and mean nothing but I suspect more newbies are coming to GNU/Linux, checking out Distrowatch sooner or later and choosing middle-of-the-road distros rather than the avant-garde Ubuntu or the old-fashioned Debian GNU/Linux. I suspect many long-term users of Ubuntu are turned off by the Unity thing, and may have visited Distrowatch in order to shop for what they want.