I strongly suspect this has entirely to do with scaning, but it still looks like I might have to do yet another controlled pressure test for TMY micro-reticulation, this time with Rodinal. Not again!!!

Hydroxide is the reason Rodinal is grainy with either exact temperatures or +/- 1C. I know Ian and I will never agree on that but the relationship between a high pH and granularity is more complicated than just softening of the gelatin (which I doubt is happening with well hardened TMax anyway).