Mrs. Obama touches the Queen
So have you heard about this? During a photo op, Mama Obama touched the Queen. This is about as big a protocol fauxpas as you can possibly make in the UK (worse than giving an IPOD containing photos of yourself to Her Majesty or a set of DVDs to the Prime Minister, which is just tacky and ignorant).
Extensive pre-trip protocol briefings were held. I guess Mz O just forgot.