Molting, Wings Growing... in pain?

[hnhobu]

During breakfast this morning CAssette flew down from his cage and into a box that we had open (it had some picture frames in it, nothing harmful). When my husband picked him up Cassette was very aggressive and he repeated adjusted his right wing. He was running around my husband's neck and biting him, without anything provoking him (we weren't trying to step him up or move him).

He's currently molting and his flight feathers are growing back in, so I'm wondering if he reaction was just shock, or if he is in pain? I've noticed him adjusting his right wing a bit, but I've never been worried about it until now.

As a test I perched him on my finger and made him flap his wings by moving towards. He made a chirp that sounded to me like he was in pain. Is this just something that comes with getting new flight feathers and molting, or should I take him to the vet?