Unless the 'fuel monitoring system' was glancing at the 'fuel remaining at destination' and making notes about what it was supposed to be and comparing it to the flight plan fuel used, it would not stand out.
The problem was not in the cockpit yet, the problem was strolling the aisles handing out drinks. She had the responsibility to pass along the report.
Same as the Buffalo Colgan F/A that did not pass along the SLF's report of sparks and flames from the landing gear on takeoff.
Both of these F/A's should be relagated to asking their customers if they'd like fries with that burger....