Eh...Gary's Rodinal is magical, I never got this good results in mine. For Tmax 400. But then Tmax 100 is quite different from 400. Despite similar name.
Wow - great results!! I'm guessing your chosen development method really helped keep that grain down. The detail of the rock beneath the horse's head in #1 is superb. I'm also loving the texture of the rock, as well as that wagon wheel. Nice tonality throughout.