Strange texture in Neopan 400 + HC110b

Was looking at a roll that was developed individually this week, and the pictures when zoomed, had this leathery texture to it. First I thought it was ACDSee rendering JPEG so that it loads fast, but it showed up also in Photoshop. Looked at the other Neopan 400 developed in HC110 this week and it was not present. So the explaination has to be with the way I develop the film. Its winter now in Shanghai, so the water coming out of the tap is somewhere around 5 degrees celcius probably. My developer is always at 20C since that's an easy timing to remember. My stopbath is somewhere in between the two. The way I process now is I do a rinse cycle with the tap water after stopbath so wash away the yellow tint in the Kodak Indicator Stop Bath so that it doesn't taint my Fixer which is colourless. My current theory is that I must have accidently gone from 15C in the stopbath to 5C in the rinse stage, shrinking the silver crystals till they crack and giving the leathery texture.

Here's a 100% crop to explain the phenomenon. Scanned at 2700dpi as usual.