When I use doors lately, many women pretend I don't exist. Is this a trend ?

Apologies for the weird title; I had to modify it to fit the sub rules.

Over the past 6 to 12 months, I've noticed a trend with women in the 18-40 age bracket.

Many (obviously not all, just many) seem to completely ignore me when we are both near doorways.

If I hold the door for them (in the way that I do for both males and females), they walk through without giving me a "thank you", eye contact or any hint that they've even seen me.

Or if we are both approaching at the same time, they will walk through and likewise pretend that I'm not there. I stop to avoid bumping into them, because they seem oblivious.

I haven't observed this happening with men at all, which seems odd, as generally I find women to be more courteous.

Is this a trend, or is there a reason why this is suddenly happening so often?

Has anyone else encountered this?