France reveres Charles de Gaulee for refusing to surrender, and saving French pride during WW2. They cherish the idea of
le resistance (one of the reasons they back the Palestinians). France's history of WW2 must focus on this (I don't know for a fact, but I've been to the Arc d'Triumph and seen the plaques honoring de Gaulle), rather than a US/British rescue of France from the Germans. There is a parallel - whether Americans like to admit it or not, there is consensus by many historians that the Soviet Union defeated Germany in its advance west, rather than the US and its Western allies.
In addition, these were events from 60 years ago. Its doesn't follow that France has to agree to eveything the US says because of the invasion of Normandy.
They're generally snotty because:
1. they (rightly) think of US primarily but also other Western popular entertainment as inferior to French entertainment;
2. no one likes to be reminded that they are on the decline as a world power. When great powers take over from each other (the only exception being the US from the UK, because of cultural reasons), there is usually a period of tension and conflict.
3. the US is missionary in its zeal to promote its interests. It outlasted the Soviet Union, which has reinforced the concept that its way and system is universally correct (ideological imperialism). This might even be true, but the French don't want to have their noses rubbed in it.
