SOME clutch slippage is normal when you're on it hard, I stress SOME. Like when you're right at that line of traction and wheel spin, alot of cars that I have driven will rev a little as the wheels catch up. Most have been higher powered ones though. My guess is it's not a bad thing, it's alot easier to replace a clutch plate than a torn up diff. I'm not suggesting that it should happen all the time, but they do slip some under hard accel, otherwise every shift would be jerky and rough.
Your clutch would not be able to slip for 16,000 miles without burning out long ago. Cobalt isn't going to help ya, it's the same clutch. If you have any intentions of driving this thing hard, alot, you're wise to invest in a quality clutch plate soon. If you race at all, you're gonna tear it up alot sooner than if you don't, and if you 'street race' alot, you'll do it too. It's just a fact of life in performance cars, the more low-end, the worse it is.