Of course you're correct, and that of course means that Blumenthal's book and his Grand Jury testimony were all lies -- of course they were.
Remember that Hillary had her own "staff" attached to the Oval Office whose entire job was to spy on Clinton and keep him and his hands off the interns. And when the Lewinsky rumor started to circulate within the WH (before Drudge broke the story) that's the time when Hillary arranged (i) that Lewinsky was transferred/banished to the Pentagon, and (ii) Hillary "representative" in the Oval Office staff was fired -- presumably by Hillary, for failing to do her job.
So the visits by Monica back to the Oval Office after her 'banishment' to the Pentagon were covert meetings under the radar of the Hillary representatives. That's the full extent of the "surprise" that Hillary experienced.