Reaction rate >0 at equilibrium

I am running a simple test problem representing dissolution of a hypothetical "glass" mineral in a single grid cell. The solid phase consists entirely of glass, the pore fluid is water. Glass dissolution is kinetically controlled. The glass dissolves and reaches the expected equilibrium concentration of glass(aq) (consistent with logK) but the dissolution rate does not go to zero, so porosity keeps on increasing even when the system is at equilibrium. I would love to know why this is happening! Input files attached. I am using TR3.32-OMP on a Mac.