Y'know, I've been trying to interpret Brun's expression in panel 4. Shocked at having run into someone, yes but, oddly enough, a little frightened (although that's gone by panel 5, mostly because she has to focus on Clinton's little detour into Crazyland).
I just feel that Brun has more than a few problems with crowds and situations where she hasn't got everything perfectly organised and categorised. Really, she's not sure she is entirely safe when she's walking around in a crowd of strangers, especially when doing something non-routine.
Additionally, notice what Clinton says about 'Claire laughing' at his misadventure. I think that's a reminder about how fraught and uncertain their relationship is; he expects her to mock him for his misfortune. FWIW, I think that she would be more likely to try to turn it into some kind of weird joke in an attempt to cheer him up but that may just be me.