To Rachel, Colleen, and Deb,
I have also seen this quite a lot. It must come from our early gender modeling. Most men grow up learning from both Mom and Dad and most of the rest of society that men must look after women and take care of them. Of course this is slowly changing in certain areas of our society but will take a long, long time to filter out this sort of sexism.
One of my teachers and two of my respected sempai in my life have been very skillful, strong women. I also have great respect for women warriors / fighters. In SE Asia I spent some time around some Hmoung women that were some of the most disciplined, effective guerilla fighters I've ever seen. Many of the best snipers I have seen and heard of in the Viet Nam war were women. I would not want any of these people after me!
I applaud you all for standing up for yourself and helping to educate the guys you practice with.
The sort of behavior you describe doesn't happen in my dojo. I have several women in the dojo that will alter anyone's mistaken attitudes about who needs "extra help" to understand the teacher.