Answer by Rory Young:
This is typical “Monitoring behaviour” during a situation.
Her head is down. Her ears are forward and raised. The tip of her trunk is curled and she is resting one of her back feet.
They explain it perfectly:
“An individual who is monitoring an event, situation or interaction or contemplating a sound, smell or object exhibits a constellation of displays including: Listening, Eye-Opening or Eye-Blinking, and J-Sniffing. The very tip of the trunk is usually curled under and around to face the object of interest. He or she may consider by looking at, listening to or sniffing, the object or subject of interest. Elephants often Monitor or contemplate an experience already ended almost as if reliving the sensations. Monitoring may be observed when an elephant contemplates its own interactions, during Object-Play, the actions of elephants nearby, human conversation or considering the bones of an elephant, for example”.
P.S. If I was on foot and she was doing this I would be talking to her in a soft, low, calm voice which they often react very positively to.