I have had one chain ring replaced on all my bikes in 20 years. That was the middle ring on a triple DA set with about 15,000 miles on it. Like you, I spend most of the time in the 30 ring. Displayed exactly the same symptoms. On close examination, the teeth had the tell tale scalloping and rounding. I am pretty religious on lubing (at least every 100 miles), cleaning (once a month or so) and replacing chains/cogs when there is wear. I usually replace the chain every 2,500-3,000 miles, with a new cog set every other chain. I agree that 3,000 miles is a ridiculously short time - perhaps you just got a defective one.