This is because these are all same-level movies that were designated for the same level, thus - due to limitations in the system - you were prompted to learn only one move at a time. You may or may not be prompted to learn one of the missed-out moves the next time HitmonChan is prompted to learn a move (missed-out moves, due to the mentioned problem, sometimes get lodged into a "queue", and are prompted to be learned the next time a Pokemon triggers the move-learning prompt), but if you notice this isn't the case, the only solution is to acquire it via playerdex's move relearner, I'm afraid.
