Stereogum readers recently voted Future Islands’ arty synthpop burner “Seasons (Waiting On You)” the Song Of The Summer, and it would seem that Arcade Fire frontman Win Butler agrees. Butler, who just got done with a massive tour of his own, showed up to Future Islands’ show in Montreal last night, and he made a surprise appearance as the band played “Seasons,” coming onstage with no ballyhoo to take on the second verse. As far as superstar co-signs go, this reminds me of the time in 2007 when Bruce Springsteen invited Arcade Fire to his Montreal stage for “Keep The Car Running.” Worth noting: There was definitely a moment where Future Islands frontman Samuel T. Herring attempted to get Butler dancing, and Butler was not biting. Watch fan-made video below.

Is it just me, or did Herring look like way more of a star up there than Butler? Baltimore pride is a real thing this morning.

[Photo by Sors-Tu?.]