And, for those who might be curious or simply don't know, the three times it's acceptable for a man to go or walk ahead of a woman (per gentlemanly etiquette) are:
1.) In a revolving door, so you (the man) are pushing it.
2.) On an escalator or stairs, so she won't worry if you're looking up her skirt.
3.) When entering a taxi, so she won't have to slide over or hike up her skirt doing so.