No, we don't know yet, though the reporter last week gave a hint when she mentioned that no one but Sinclair would have Garibaldi and implied there was something dishonorable about the way his last assignments ended.

It just struck me that Garibaldi, who otherwise enjoys hanging out with Londo, really looks uncomfortable during the banquet, when based on the information the viewers have at the time one would expect him to enjoy himself much as Ivanova does - but it makes sense if one remembers he's not on the wagon for that long, and it has to be really hard for him.