Do you have any videos of how Sprouty Boy interacts with you? A video would tell a thousand words.
IRN take 2-3 years to sexually mature, so it is probably not hormones yet if he is only one year. Which makes me wonder if it is related to something else. Possibly how you approach Sprouty Boy or how you position your hand when reaching toward him. This may simply be
a body language misunderstanding and not true aggression. It is natural for a growing young bird to develop more independence. A little baby will want extra physical and emotional support, but as they age they want to do more on their own. My best advice immediately is to take a step back and don't get frustrated with Sprouty Boy. You want to respect his choices. If you don't give him the distance when he is requesting this can turn into a bite.
For your reference:
Do Animals Bluff?
If you have a video it will really help us understand and give little tips that will help you both succeed.