that was possible more a guess ;)
where are from your Möderndorfer?
someone born in Carinthia or Styria? so if - you can ask at diocesan-archives to get ancestors info.....
go backwards in your line to find out more...then you can always - maybe - find a connection ;)
a wild guess and research on nobility will not bring the result ;)
the nobility in Carinthia was named "von Möderndorf" not Möderndorfer.http://www.genealogy.at/deutsch/adelsgeschlechter.htm
there are 42 results for the lastname Möderndorfer in Austria in this countries - and not any of them will be of nobility:) - you see that many of them from the Gail-valley - so named after the place Möderndorf.
Tirol (1) http://www.herold.at/telefonbuch/m%C3%B6derndorfer/