IMO when normally mellow iguanas display dominance like that, they shouldn't be petted or picked up. Your ig is fine, but it's in his nature to show dominance once in a while. But never jerk away from him when he starts a display, so he does not connect cause and effect.
IMO that wide-mouth gape at your leg is part of male iguana romance activity. He might even take hold of part of you. It's common for "in season" males to act it out on their owners. I hope he keeps his gentle attitude. If he starts getting rough, fend him off with a broom.