Pits are very susceptable to those hissing fits as they are so aware of the surrounding them live in. Very seldom will you be around the cage when they do not know it. If they see anything that is startling to them or triggers the defense mechanism in the little brain that runs them here comes a hisser as I call it. Most of the time they are bluffing, but we do have some individuals in the collection that will bite at times. I have one southern that is an touchy animal to say the least and she loves to play her role as godzilla on a regular basis. The only way to get her to shut up when entering the snake house is to pull her out handle her for a few minutes and put her back up, after that she is fine and settles down. If left to her own devices she will continue for hours and even bite if you make the mistake of reaching into the cage. But after the handling session she is tractable and easy to work with.
Sonorans though are some of the calmest of the pits we have in most cases and as you little guy gets older with a little handling will settle down.
Quit scaring the poor little guy to death you "giant bent on destroying the poor little thing". ( that is a joke, but meant to give you a little perception) LOL. All kidding aside move slowly, handle often and you will be fine.
Here is an off topic pic. a resident of this forum sent that I think is really cool. (Albino American Alligator)
Good Luck,
John Cherry
Cherryville Farms

Cherryville Farms - Reptiles