I can so relate to this! Whenever I'm out alone and sit down at a cafe or a restaurant I always look for the window seat, the one where I can enjoy watching the passers-by and play with that eye contact "game". As a street photographer, I'm used to noticing people all around, but you said it nicely that it's also a fun challenge being in there like a mannequin and letting yourself be seen (in the safety behind glass :D)