This shouldn't be surprising. The "stimulus" effects have, for the most part, run through the economy leaving only traditional drivers of growth. Again, 2/3rds of GDP is consumer spending. With "underemployment" near 17%, consumer spending will not grow considerably in the near future, thus neither will GDP.
The Federal government has attempted to replace the consumer in this equation but increases in Federal spending have been mostly offset by decreases in municipal and state spending (think NJ). Finally, businesses are only just beginning to see top line revenue growth which is necessary to enable them to begin spending again.
Thus, GDP growth will continue to slow over the next couple of quarters as we continue to get our feet back under us. There may be enough good news to keep equity markets moving but a correction of some sort isn't out of the question yet.