It has become commonplace in the first few months of Obama's presidency to report occasions when he either didn't know tradition, etiquette or protocol, or else he didn't care. Whether snubbing Britian by returning a bust of Churchill given as a gift, giving inappropriate gifts to Gordon Brown and Queen Elizabeth, or demeaning America while visiting another country, Obama shows such a complete disregard for presidential behavior that it's no longer considered outrageous. (This, by the way, is a common practice among Liberals -- they simply wear down our sense of outrage.)
The most recent un-presidential move was Obama's bowing (see: kowtow) to King Abdullah of Saudi Arabia. This violates centuries of American tradition of refusing to defer to royalty. Interestingly, the White House apparently denies that Obama "bowed." The excuse, according to an Obama aide, is that Obama is taller than the king, and simply stooped to shake hands.
Decide for yourself:
Despite the White House's "denial," if Obama's not bowing, then he saw a quarter on the floor. It's pretty clear that when it comes to Obama's actions, the most common comment on President Obama for the next 3+ years will be "Well, what did you expect?"