Right there, last pic. The web of your thumb is creeping over the tail.
And visible in picture #1 and 3, to a lesser degree.
And if you took your off hand and simulated recoil, the pudge of your hand would be shoved even further up into the hammer-bite region. Under real recoil, the gun and hand will move in an unpredictable way, sometimes shoving the skin into the snappy hammer bite, sometimes not. If you can make it happen simulating recoil, it will happen eventually while shooting.
As to why it is happening now and not before ... my best guess is that you've either started gripping higher on the gun or changed the way your support hand interacts with the dominant hand.
Need to figure out if it is the slide kissing me or the hammer.
I'd guess hammer, but if you really want to know for sure, put on a cheap and thin white cotton glove and mark it in black where the grip safety sits, black and red marks to the side are slide, red marks in the center are the hammer.
(hint, slide grease and carbon provide the black, YOU supply the red)