No, it's a bank that you were required to call.
pj
chgo
He "called" the right ball in the right pocket. As described, it would have been 100% obvious to everybody there which ball and which pocket were intended.
Had the ball gone into the side after 3 rails, it wouldn't have been good. Your interpretation brings to mind silly bar rules requiring that short rails be called as "banks".
Sometimes, if the situation isn't addressed explicitly, the players/referee needs to consider the intent of the rule.
How can the pocket be obvious if the path to it isn't?
pj
chgo
Simple. As it relates to the accidental path in the situation posed by the OP.
The straight in path for that ball to that pocket was certainly obvious.