There appears to be two parts between the bearings.
1. Support ring:
http://www.cscmotorcycles.com/Suppor...-p/z50-109.htm
2. Spacer or inner bush:
http://www.cscmotorcycles.com/Inner-...-p/z50-110.htm
Depending on how the middle of the hub is machined, it's possible the bush fell below the axle line while the axle was out. The worry is on the dealer and distributor.