The other way to look at is that these employees wanted to sell their shares, to lock in their gains and diversify. They could sell them as part of the IPO, or they could wait 6 months after the lock-out. They choose to sell immediately, which means the employees at least think it's a bubble.
Employees know what deals are on the table waiting to close, and new product announcements, and all sorts of things related to the stock.
If they think the stock is going to double in the next 6 months, do you still think they'd sell? Even if they say "It's my money and I need it now!" brokers would be happy to offer a loan using the shares as collateral for any immediate money needs.
If somebody is selling, they don't think the shares are about to double, plain and simple.
