Rei turns around. She climbs up a stair and looks at Shinji.
Kendrix: Rei has a habit of placing herself directly before people and looking them in the eye when she's angry. We see it again in ep 16.
A bit on this mannerism even survives into Rei III - she minimally tilts her head up when talking to Kaworu or when she betrays Gendo, but it isn't a full body movement anymore, only a faded afterimage.