Yes, what your sister experienced is concerning and should be evaluated by a doctor as soon as possible. Even if this was the first time, it can become dangerous, especially if it happens while crossing streets, walking alone, or in unfamiliar places. If you have any further questions or need more clarity, please consult with a psychiatrist. If you`re in Texas, we welcome you to reach out to www.MidCitiesPsychiatry.com, we`re here to help you.

Practice some relaxation exercises every day such as meditation or breathing exercises
Drink ample water every day
Have a healthy diet and include nuts such as walnuts and almonds in the daily diet
Limit the intake of alcohol
Stop all forms of tobacco use
Sleep for 7 to 9 hours a day at a stretch

What you are describing could be as common as an individual being preoccupied or distracted by other thoughts, yet could be as complicated as a seizure like state. It would be best to have her talk with a psychiatrist and or neurologist about the experience in order to safely rule out more dangerous possibilities, as well as to prevent a future recurrence.

Lance Steinberg MD, Inc.
Assistant Clinical Professor
UCLA (Geffen) NPI
1(818)224-3540

See this link...
https://psynso.com/absent-mindedness/