Queens-bound buses rerouted in Midtown
As a result of new traffic regulations prohibiting left turns from eastbound 57 St to 3 Av,Queens-bound QM2, QM3, and QM20 buses will now use 59 St instead of 57 St between 6 Av and the Ed Koch Queensboro Bridge.
To accommodate this change, the bus stops on 57 St at Madison Av and 57 St at Lexington Av will be moved to 59 St at Madison Av and 59 St at Lexington Av.
There are no changes to the stops or travel path of Manhattan-bound QM2, QM3, and QM20buses, which will remain on 57 St and continue to stop at Madison Av and Lexington Av forDrop-Off only.
Source http://web.mta.info/nyct/service/planned_servChanges_QM2QM3QM20.htm
I think that this is better for people who use the Lexington ave 59 street station NQR 456 trains as it reduces walking time.