When will it be time to panic?

Stocks end higher for sixth straight week, tech leads

Turns out, there was some actual positive news, and stocks ended higher again last week.  It's old news, though, meaning it doesn't reflect the tax hikes that took place in January.  Still, the relatively good earnings are a good sign, the trade deficit came out smaller than expected, China's growth bodes well for the global economy, and there are signs that employment may pick up. On the other hand, from a few days ago:

NYSE Margin Debt Rises To Fresh Five Year High As Short Interest Slide Continues

[margin debt]  rose for the fifth consecutive month, reaching $331 billion - the highest since February 2008, when the market was declining, and back to the levels from May 2007 when the market was ramping ever higher to its all time highs which would be hit 3 short months later, and just as the subprime bubble popped.

 I just have to wonder when panic is going to set in.  I think we'll see some more positive action for a while.  The market almost can't help but rise.  But, I really think that's going to change soon.