Superstition? Religious Ritual?

I took Walker Evans on a long walk today, including passing Women's and Children's Hospital on both Bryant Street and Hodge Street.
Just after we passed the hospital going from the direction of Elmwood Avenue toward Delaware Avenue on Bryant, Walker stopped to sniff a tree, one of I think 528 sniffing stops he made.
A woman walked by us in the same direction, and just as she passed me, she tripped over a crack in the sidewalk; she immediately muttered "fuck" beneath her breath. But she continued walking, and as she did so, she turned around 360 degrees four times, and after the fourth time, she performed a Sign of the Cross and then kept walking without further turnarounds.
I really wanted to ask her what and why she did that, but it seemed like it would have been an intrusion.