Fliifast1, please read carefully:
I donīt wrote "aft airstair", i wrote "stair at the aft entry"
During Pax debording out of door 1L normally a stair is positioned at aft entry.
It is not seldom that lower Gate of the door meets the stair.
During debording of HF 737-800 i often see a change of hight at aft door up to 30cm.