Ever think you see someone you know?

On the train to work this morning I thought I saw someone I knew, but I wasn’t sure. Ever have that happen – think you see someone you haven’t seen in years? I started do that thing where I’d look at the woman and then look away before she realized it, trying to figure out if I knew her. Of course after a minute or two the woman took notice, as they always do. Aware that she knows I'm looking at her, I start desperately searching my memory to see if I know her (because now I’m being rude and snubbing her if we know each other) and I’m also afraid that now she thinks I’m some strange guy staring at her, if we don't. To make matters worse, she got off at the same stop I did, and went the same direction. Great. Now this woman thinks I’m a stalker.