Also realize that Page was not a very well known entity in DC, and Judge may not have know he was minor player on Team Trump, and although Trump was real target, FBI never raised Trump issue with FISA judge.
The key concept is that the FBI used the FISA request on Page to be able to surveil anyone on the Trump campaign, including, it can be assumed, Candidate/Nominee/President Trump.
But unless such extra surveillance revealed crimes committed, the FBI has never revealed who else was surveilled other than Page.
That brings us to the next obvious question for appropriate FBIers to be asked: Who else, other than Carter Page, was surveilled under the FISA Court approval obtained for Carter Page?