About this scene
Grocery store, mid-aisle, late morning. She's in her thirties, cart parked, list in her hand, basket on her arm. The flash is at the end of the row. She does not pretend to keep shopping. She stands still and just looks for a long beat, maybe twelve seconds, before she even rotates her body toward the shelf nearest her. When she does pretend, she picks up a product without registering what it is and turns it over twice before putting it back.
What to watch for
The unhurried stare is what most public reactions don't deliver. She is not concerned with hiding the watching. The list in her hand falls slightly when her arms drop. She does not raise it back up. The product she eventually picks up to fake-shop with is some kind of canned vegetable and she does not actually read the label. She puts it back on the wrong shelf, and you can see it visibly out of place when she walks away.