Please help my GSP!

I can't tell if something's wrong with my GSP and i don't really trust the internet, but he's been acting strange lately. He is about 2 inches long and I've had him for 6 months, and over the past few weeks he has been baring his teeth and biting at me when I pas by. Is this just his way of saying "Give me food", or is there something wrong. He eats regularly and a variety of frozen and freeze dried foods, and this is the first time he's acted like this. Please help, I just want the best for him!

he has plenty of decor and right now he is in a ten gallon, but I ordered a 39 gallon off of ebay on wednesday. He eats fine and has a large belly for a while after, and the sg is below 1.017 but i have been adding about a tablespoon a week with 1/5 water changes a week. I recently checked the water with a test strip also, and it showed all levels as being ideal. Also, this first started shortly after a party I had had, and one of my friends suggested he is just used to when he sees me hes getting fed, and so he's just preparing to eat. Any ideas?

ok thanks a lot for the help and yea I have noticed he has been acting more cramped up lately, so I found him the tank. He'll probably be much better with more space! Also, here's a picture of the little guy! His name is giblets, pretty accurate for a puffer!

yeah i've noticed that came up recently in the past week or so, but I think it's mostly being cramped up. Like i said, next week the tank should be in and he should probably be a LOT better!

also I was wondering should you clip your puffers teeth if they get to long by soaking them in clove oil and clipping their teeth, or is it bad for them? also, how can you tell when their teeth are too long?