He doesn't like me anymore

[growing zoo]

I have had Kevin (veiled) since he was 3 months old and had such a lovely relationship with him, coaxing him to eat when he went off food for 4 weeks, lovingly spraying him and dusting his food and when I read on this forum that veileds can be aggressive I thought that I had the pick of the bunch as he never had a bad bone in his body........BUT........since reaching his 10 month mark he has started hissing at me, puffing himself up and today as I sat chatting to him he lurched towards me, hissing
Does he hate me all of a sudden?
Is this puberty? Will he stay hating me if it is puberty?
I don't want to be scared of him !!!!

Also I have noticed that he circles his cage most of the time, its 3ft by 3ft by 1ft dont know if this is a sign of anything??

 

[Texas Ranger]

It could be that he is just growing up and becoming a Man. He is just claming his terttory. I noticed my panther becan pacing in circles in his cage when he was around that age. So I upgraded him to his adult cage. A 2x2x4 size. Once I switched him he was fine. But he never got aggressive. Some do and some dont. I would recommend getting a bigger cage. And try not to be affraid of him. But also just give his space.