I'm guessing it's 1.0.6 as borders.c is a few days old. borders.c was changed so that mwmborder no longer creates a minimal button relief. It's either no border or raised/sunk.
Removing mwmborder from config restores the minimal window border, but not button border. I changed the 2 : 2 to 1 ; 1 on my copy of borders.c to return behavior. What's the planned way of having minimal but existing relief in buttons?