some of the characterisation is maybe a little out (I'm still not convinced Londo would have set Garibaldi up and destroyed his life 'in a minute', given how sentimental Londo is about notions of honour)
In my opinion, the guest actor playing Kemmer overplayed, by a bit, the character's rigid stiffness during the majority of the episode (before she forgives Garibaldi).
The way I see it, she was a very young looking female in a very important position. I think her general demeanor and stance would be dour and rigid in an attempt to be taken seriously. Then throw in Garibaldi's past relationship with her and she is seriously tensed up for the remainder of the episode.
I gave it a D because I think Major Kemmer's a "---"itch.