[bert64]

The link-local address is generated when you first enable the interface (ie when you load the drivers for your NIC), it won't change unless you manually force it to.

Linux will use EUI-64 if left to its own devices, or privacy extensions if you're using something like networkmanager. This makes sense because a desktop oriented distro will typically use networkmanager while a server oriented distro will not, and having a predictable eui-64 address is usually beneficial for a server.