Don’t pet the animals.
If they were walking away, Im guessing she turned to meet the bison head on?
Ive recently been 40 feet from one, but we were on a bus, he stopped because he wanted the road to himself for a few minutes..
otoh. I wouldnt get within 500 yards of bison unless there was a barrier between us strong enough to stop a F-350 quadcab dually doing about 35 mph.
I used to travel to Wyoming every November to hunt elk on horseback with a guide. He was a younger native and wise beyond his years. He told me that guys like me from the east need to be watched so we don't do anything stupid. I didn't live up to his expectations but apparently the Darwinian behavior is prevalent in east-coast humans. Stupid is as stupid does.