Weird moment

As I was waiting at the 86th street station, for a Line 1 subway train to get back to Columbia,  an express Line 2 zoomed by with the usual deafening noise and its whiff of better left unidentified odors… And then, as the train was vanishing into the tunnel, I had the fleeting vision of a red wreath attached to the back door! (As the thing could not be a life-preserver (!) I wonder what it was. Or if I urgently need to check my vision…)