Its not a bug. Program displays "1450 Mb" because its more precise than "1 Gb". On the other hand there no big difference between 11.3 Gb and 11.2 Gb, that's why program change unit to Gb after 9 Gb.
That would make sense if the entire reporting is consistent. At present anyting less than 10gigs is reported in four digits (more precise as you put it) and above 10 gigs is reported in 2 digits. Why would make part consistent and not the other?