About this scene
Barber shop, three chairs, two customers, late afternoon. She's a redhead in the chair getting a cut. The barber is mid-trim with the clippers in hand. The flash happens at the front window from the sidewalk side. The redhead sees first and freezes mid-mirror-check. The barber tracks her eyes and clocks it second. Neither of them speaks for ten weird seconds. Then the barber goes back to the cut and the redhead watches the window in the mirror for the rest of the appointment.
What to watch for
The barber's reaction is the second story. He's a professional and he treats it like a professional. Clippers down, eye contact with the redhead in the mirror, brief raised eyebrow, clippers back up. The redhead does not break her view of the window. The cut continues. Watch her face in the mirror. She is half-smiling for the next two minutes and the barber is pretending not to notice. The shop bell does not ring during the encounter.