Living in Texas politeness is pretty much ingrained. For instance, last night as my husband and I was leaving a restaurant a guy who was about to enter in the same door we were exiting held the door and said go ahead. We both said "thank you" and kept it moving. He was about 28-32 too.
Hell, even at work, if a male coworkers and I walk up to a door he will grab it first and wave me in then he follows behind.
Even I do it, if I open a door and someone (regardless of gender) is coming thru that same door I hold it open for them.
Its not about seeing someone as being "weaker" its common courtesy and where I'm from its as easy as saying please & thank you. Is it that hard to take 5sec out of your time to hold a door?