Trakis might have set her on Londo a long time before the ep starts, but have figured that it takes a while to get close enough to be able to get to the Purple Files. That would give the two of them time to get a acquainted, and also once she fell in love she'd probably have started stalling, which explains why he doesn't buy her excuses (besides her inability to lie) and gives her the mind-probe thingy.