Im seeing this also - using 10.9. seen it on 2 discs
both show up as 'data' discs.
Drive Information
OS device name: /dev/rdisk3
Current profile: DVD-R
Manufacturer: TSSTcorp
Product: BDDVDW SE-506AB
Revision: TS01
Serial number: ---
Bus encryption flags: 1F
Disc Information
Data capacity: 4.6 ...