For real it is very doubtful. East Germany nationalized all the lands of the junkers so they cannot claim anything. The memory of Weimar was basically the one of a bourgeois republic under siege from reactionary and fascist. Nobles=reactionaries. Communist firmly believed in establishing a new State without them (or despite them).
If aristocrats looked for refugee they would better look elsewhere. Early purges in East Europe had the aristocrats has the first in the list (non revolutionary and reactionary landed class to say the least of them) it would be dangerous to claim in public status of aristocrat, no benefit of it politically. Well, except being stripped of any right and expropriated.
Besides there is a memory and public awareness, independent of propaganda, that all nobles were reactionary to the Weimar Republic and it did not help they conspired for its overthrow and later gladly accepted the III Reich. With that kind past behind them it is doubtful they will have firm democratic or antifascists credentials in the eyes of the communist party.
To claim honours would also be against the task of building a workers' and farmers' state that would become a classless society as it was publicly stated. So any one that claim honours would be pursuited, demoted and thrown out of any political position if he claimed any ''von'' status.