Face rings a bell

An old lady sits opposite me on the metro. Another lady of similar age comes up to her and says that she’s been looking at her for a while, knowing full well that she knows her, but unable to remember how or from where. The first lady admits that she was thinking the same thing about her; I know that face, but I can’t place it. They stand in silence for a moment, then the first lady says “I’m sure I’ll remember in about an hour’s time”. They both laugh and the second lady gets off the metro.

The first lady sits a while longer, lost in thought. Then she suddenly stands up and heads for the door, realising that she’s missed her stop.