Mint-z Less Installation

A bit more on the Linux Mint upgrade on my Thinkpad T60p.
Don't know what the hell happened but I ended up with a Linux Mint (MATE 32 bits) installation without any theme except the default installed.
Missing was my favorite GTK one, Mint-Z...

I thought something went wrong during the installation, and maybe the theme got left behind (strange since everything else works A Ok...)
Anyways, booted onto the USB key I used to make the install, and lo and behold, same problem...
In the end, simply copied the Mint-Z from an Linux Mint 13, doesn't seem to be any problem.