The release of Apple's (AAPL: sentiment, chart, options) iPhone 3G was supposed to be one of the biggest events in the technology sector this year. So why has the stock slipped more than 1.7% so far this week? According to Silicon Alley Insider, the answers can be found in the margins.

The tech blog reports that Travis McCourt, a Morgan Keegan analysts, "whacked his gross margin estimates for the June quarter, fiscal 2008, and fiscal 2009." McCourt believes that Apple's margins are "likely to be down significantly" year-over-year because of "new/refreshed products and because component prices have gotten more expensive."

I would like to add inflated investor expectations to this equation, as the stock's Schaeffer's put/call open interest ratio (SOIR) of 0.81 ranks above just 35% of all those taken during the past year - indicating a preference for bullish call options over put options. Meanwhile, Zacks.com reports that 15 of the 18 analysts following AAPL rate the shares a "buy" or better. Laying this sentiment against the rather poor reaction to the iPhone 3G's respectable weekend sales numbers, and we have the makings of a "sell on the news" event.