Maybe Mason was frightened by her display in court that day (Friday) and thought the jury might have seen it. This is when she was looking at Mason but pointing to Baez saying "You, get him" with that vicious look on her face.
We all seem to have been shocked by it and I daresay that we know what ICA is capable of better than Mason. Up until the trial he had been to see her TWICE in a whole year. Whereas we have poured over her interviews, all the depos and interviews of witnesses, all her phone records, photobuckets, Instant messages, jail visitations etc.
There is no way I would ever believe that ICA suddenly changed whilst in jail, as far as I'm concerned, she is still the pathological, lying, manipulator she always was and she MUST be doing it to her defense team. I'm pretty sure that Mason doesn't know which way is up with this girl - I think he would have been worried about the jury seeing her display and although we can't ever know this, there is probably something going on with her testifying or not testifying.
Mason must have also brought Ann into the mix or demanded that she come back as it's usual that Ann shouldn't be tainted with this phase of the trial, and that also speaks of trouble in the team.
eta: I should have made it clearer that I think Mason is aware that this jury has now been tainted by the actions of his client - he wants a new jury, and it goes back to her actions on Friday.