Are you sure it's right to blame NBC? ...did you not precipitate thru an early walk-in? In my case, my interview has been scheduled exactly the day after my 5-yr anniversary. (I guess, it helped that I did not mess w/my FP appointment)
In any case, the good news is that you have a new date (not far off, at all) - unlike many that are left in limbo (when they walk out the building)...
My wife didn't go for an early walk-in (not in Houston though). But she too was scheduled for a before 5 years interview (20 days before the anniversary date!) and now she has to wait to hear for an approval (& oath letter).
Albeit I believe my early interview date was precipitated by early FP walkin!
I did have genuine travel plans; my original FP was Friday of the Labor Day long weekend.
TIMELINE
5 Year based N-400
GC Date: Oct 27, 2004
DO: Houston, TX
*****************
07/31/2009 (Day 01): N-400 Mailed to Lewisville, TX (Priority Mail with Delivery Confirmation)
08/03/2009 (Day 04): N-400 Delivered @ Lewisville, TX
08/05/2009 (Day 06): Check Cleared
08/10/2009 (Day 11): NOA Received (Priority Date: 08/03/2009)
08/12/2009 (Day 13): Online Case Status changes to RFE (Finger Print Notice)
08/18/2009 (Day 19): FP Notice Received
08/25/2009 (Day 26): FP Done (Original Appointment Date: 09/04/2009)
09/05/2009 (Day 37): Online Case Status changes to CASE SENT to DO
10/03/2009 (Day 65): Missing Interview Letter arrives at the Door Step!
10/20/2009 (Day 82): Original Interview Date
.
10/28/2009 (Day 90): Rescheduled Interview Date
mm/dd/yyyy (Day x): Oath Letter Receipt
mm/dd/yyyy (Day x): Oath