Some fans apparently took it upon themselves to go home with a few souvenirs after Game 3 on Sunday.
A "handful" of seats were removed from Nassau Coliseum after Sunday's overtime win against the Capitals. In Section 305, the folding, cushioned lower portion of one seat appeared to be pried off, possibly with hand tools. At Tuesday's morning skate, a folding chair was positioned at the seat (Row K, Seat 7) as a placeholder, but workers soon installed a new bottom portion of the seat (green, not blue like others in the section).
Coliseum staff realized the seat was missing shortly after Sunday's game.