It is probably a good idea.
We all have fluctuating fasting blood glucose, and some docs seem to require 2 tests over 7mmol/l for a diagnosis.
It is the HbA1c that is best done several months apart, since that measures 'average bg' which won't change much in a few weeks.
The NICE guidelines urge that any discrepency between HbA1c (yours is diabetic) and fasting blood glucose (yours is low prediabetic) should be investigated, to check why. It could be a bad test/lab process, it could be that your fasting bg was lower than usual... Lots of reasons. I would go with the flow and ask the nurse what tests she has been asked to re-take and discuss it with her. Should shed more light.
Hope that helps.