There is much more light in the whole Nikita's apartment when Michael enters that before, when Nikita is talking to her friend. It does not only seems as if someone had turned on some lights but as if it was a complete different time of the day :) .
Phrased to avoid spoilers - There's no way the bad guys could have known all they did to prepare their assassination attempt so elaborately, but NOT acquire the piece of info they work so hard to obtain.