I think that, depending upon who was in the room each time, they probably all saw different things.
We saw Alexander taunting Perez (who was in the cage with Nadia and Cami) on the night Katie P went in, we saw him shouting over to Perez when he was headed to the DR one time, calling him out I think they call it (it sounded like he was challenging him to a fight), we saw Alexander blowing kisses at Perez.
Of course, we also saw some of what Perez did.
One can only assume there was other stuff we didn't see, from both parties, that some or other HMs would also have seen. I imagine there could be things Nadia saw that perhaps Kav didn't, and vice-versa. Of course, Kav would see it more from Alexander's perspective and Nadia from Perez'.
So really, we don't know all of what went on or what Nadia was referring to, not helped at all by her refusing to elucidate.