The drivers are not pink; only the cheesecloth cover is pink.
No one outside of Grado knows if the drivers are any different.
Thee were made during a transitional period:
1. John taking over from Joe Grado
2. changing from modifying outsourced drivers from Primo (HP-1000) to "making" drivers in house
3. engineering 'affordable' and 'profitable' headphones for consumers vs. Joe's cost is no object HP-1000
Best guess is one early batch of sourced cheese cloth was off and changes color.
IME the pinks all sound great/better.
Could just be they're from a time when Grado made fewer headphones more carefully.
For all we know, John assembled the early RS cans, he did assemble the HP-1000 for his uncle....