yeah i think that's what it is. I used a little saliva and rubbed it off with my shirt. worked just fine. not going to fight the inevitable crud pile that collects on all my keyboards. it's just me being OCD
Get an iskin for your keyboard. When I first got one I really hated it, but now it feels kind of foreign if it is off... I am waiting to be able to get them for the apple desktop keyboards, so they can match the feel of my laptops. I really like the small bit of resistance they provide.