Catcher forgets number of outs

[John Robertson]

How would you rule on this hypothetical situation?

Runner at second base with one out. Batter hits a fly ball near home plate. The catcher makes the catch near her team's bench area for the second out of the inning. Mistakenly thinking it is the third out of the inning, she heads to the bench while carrying the ball. As soon as she enters the dugout with the ball, the umpires call time.

Would this be considered intentionally carrying a ball out of play, or would it be unintentional? This decision affects the the awarding of bases to the runner who was on second base, of course. (I believe the baseball rule book says that if a fielder loses track of the number of outs and carries or throws the ball out of play, it is still deemed to be unintentional. The softball rule book in Canada does not address this.)