My first thought is to make sure he is not in pain, as bunnies can display aggression when they are hurt or ill. So I just want to be sure that that is not the case.
If not, then did this behavior start happening when he had the run of the apartment? But he was fine before then? Never lunged – only with this new freedom?
IF this has happened at the same time, this is what I think could be going on:
All this new extra freedom, new space – Yeah! But at the same time it can be a bit overwhelming, even a little frightening, especially if he’s only been with you two months. He is now allowed to go into a place that is occupied by several people. – The general territory of everyone
soooo, I bet he found a place that he feels secure, and some bunnies, either out of fear or dominance will defend this "prized location"
He may have found that growling and pouncing actually made someone back away – even if you put him back in his cage, he may still associate that this behavior worked in some form.
I don’t usually worry too much about a bunny defending their own pen or cage, unless they bite. I just move slowly and allow them to have "their space". But in the rest of the house, I want my bunnies to be able share territories – part of the reason I do that is because SOMETIMES territorial bunnies will insist on marking that area to claim it along with aggression.
Also, aggression can escalate, so if that happens, you’d want to prevent that. It may die down as he gets more comfortable, but if it only gets worse then I have a few suggestions to break help break this habit:
Wear a glove that will protect you from any potential bite or scratch so you won’t pull away in fear. (Make sure the gloves have your scent – some strange smelling glove that you had in storage may just make him fearful. So how do you get your scent on the gloves you ask? You can put them in your dirty laundry for a day, or sleep with them. GOOFY I KNOW. but it works.
And when he is out in the general territory and he guards a particular place, just rest your hand there. When he pounces, growls, bites whatever, -do nothing. Don’t get mad, don’t be afraid, just hang there. Move a little, slowly, and he may get upset. Just talk to him gently, and if he’ll let you, pet him. Some bunnies will settle down once you offer them pleasure – and I haven’t found that they associate this as reward for bad behavior.
When he calms down, even for a short time, leave him alone. Plus, you don’t want to keep pushing him. Just do this in short sessions, everyday. Do this over and over and hopefully the repetitiveness of leaving him in peace when he’s not being aggressive will teach him that aggression doesn’t work, and he can stay under the table without having to fight for it.
This can take time – When I first got Jack, he was a growler and a lunger. It took me three weeks to get him to stop. And he’s a big boy! Even with the gloves, both my husband and I would flinch, so we learned to close our eyes.
Keep us updated! Good Luck!