It's all about inventory levels. Fourth quarter US GDP growth was 5.7%. Per the LA Times, it was "driven largely by a rebound in manufacturing and better-than-expected gains in consumer spending and commercial investments." And what indicated the rebound in manufacturing? A big jump in inventory levels that made up 3.4% of the growth rate. The NYT more pessimistically characterized it as "businesses ran down their stockrooms at a much slower rate than they had earlier in the year." Either way, a jump in inventories could be a one-off, and is not in my opinion, indicative of a sustainable recovery.