Is it a social blunder not to kiss a woman on the cheek when you meet her? On the same level as asking her out in an elevator at 4 AM?

Not really a social blunder, just possibly slightly awkward, depending of the context. When I arrived in France as a little kid I found all that kissing disgusting and recoiled when someone would try to kiss me on the cheek. I later forced myself to suffer the ordeal in order to fit in socially. Now it's pretty much a habit, so I wouldn't be surprised if I eventually accidentally creeped out an American girl by kissing her on the cheek.