Who put bubblegum on Marcus Stroman's hat? A Blue Jays dugout mystery

Marcus Stroman was sitting in the dugout on Wednesday night, watching his team take on the Orioles, when he felt a strange presence on top of his head:

After pulling the bubble off of his hat, Stroman looked around to find the culprit. Curiously, no one around him seemed to have any idea who had done it. Could it be because the bubble had come from inside the dugout?

Stroman's seatmates suddenly found themselves very interested in something far away, and seemed unable to offer him assistance in solving this puzzle. Could it have been have mild-mannered R.A. Dickey or the very serious and not at all goofy Munenori Kawasaki? No, thought Stromann, looking up:

Aliens. It was definitely aliens.