The details were never provided but based upon everything that's...

The details were never provided but based upon everything that's been said over time I'd be willing to bet that there was a small incentive for early parties signing. The reason I say this is because it was originally indicated in conversation that this may happen, it's commonly been the case in other projects (thus almost accepted practice), and the ongoing descriptions of achieving an average price across all tollers supports the idea that some tollers get discounts.