The only strange thing is that if I ask "About Gimp" it says it's 2.6.2 version.
... are you sure, you've downloaded the newest release?
I've just redownloaded Leopard / Intel fromhttp://gimp.lisanet.de/Website/Download.html
and the menu entry "Help -> About" reports 2.6.3.
BTW, the PPC version is still 2.6.2., but the new 2.6.3 will follow soon.