I agree, it's a great building.
A while ago, it was mentioned in an interview from either Stern or SHoP and they did say it's supposed to turn color to a greenish color over time.
A recent article mentioning it:
The towers, which were designed by SHoP Architects (also known for Brooklyn’s love-it-or-hate-it Barclays Center) and developed by the luxury mega-developer JDS Development Group, will be made up entirely of rental units ranging from studios to three-bedrooms. The distinctive copper cladding is reminiscent of the weathering steel on the Barclays Center, which quickly turned rust-colored. Similarly, the buildings' copper, currently shiny, will soon age, coloring the buildings a vibrant green