President Obama admits spying on allies, see this CBS News piece for details. This forces our EU allies to act offended, as though we've done something odd. Spying on allies is common; what is uncommon is admitting one engages in the practice.
It is like announcing at a dinner party that you belch or ______(fill in one of the less attractive things done in conjunction with a toilet). Everyone knows it is done, yet many are offended by your rudeness, your failure to realize it is not spoken about.