EB-1B I-485 delayed for 8 months

[pmsreekanth]

My I-140 has been approved in EB-1B category in June 2013.
Filled I-485 on October 30, 2014. Received EAD on February 6, 2015.
Still I-485 is pending. Tried to submit a SR online. It says the case falls in posted time frame and cannot take SR.
Is it normal to get delayed this long for EB-1 category, after EAD approval.

[inadmissible]

This is not an unreasonable time frame.