Flaps setting was changed at T minus 56 seconds from 30 degrees to 40 according to the NTSB, is that normal in a stabilized approach on a 737?
It might be a tad low and late, but I wouldn't think really outside the envelope.
Approximately passing WARIN - 860 feet and 2.5 miles from threshold, assuming 135 kts.
http://flightaware.com/resources/air...C+RWY+04/png/1
I stand to be corrected by a current 737 driver.
4 seconds before touchdown they were 134 kts, flaps 40, pitch up 2 degrees. Which seems fine. It just appears* they flared a bit high - over-corrected - planted the nose.
*videos, NTSC numbers, pilot eyewitness on ground.