acroguy----yes if you had a runway approach selected already and you didn't touch the FM/FMC it would still show the Runway and waypoints on the approach, the only problem comes if they didn't sequence correctly and you subsequently carry out a missed approach and select NAV/LNAV........oops.
Other than that the Map will still show you the Runway correctly, so if they had programmed a RWY before and not cleared it ( why would they ? ) then all they had to do was look at the Map and say "ahhhhh how come the runway we want is 5 nm away over there?????? Map shift?????? No we have 2 GPS's Mmmmmmmm bugga"